/* Lecture design system: reading layout for every lecture page.
   Shares colour tokens with styles.css, so dark mode works everywhere. */

.lecture {
  max-width: 740px;
  font-size: 16.5px;
  line-height: 1.72;
  letter-spacing: 0.005em;
}

/* ---------- hero ---------- */
.lecture-hero {
  padding: 8px 0 22px;
  margin-bottom: 8px;
  border-bottom: 1px solid var(--border);
}
.lecture-hero .eyebrow {
  margin: 0 0 10px;
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent);
}
.lecture-hero h1 {
  font-size: 32px;
  line-height: 1.22;
  letter-spacing: -0.01em;
  margin: 0 0 14px;
}
.lecture-hero .meta { display: flex; flex-wrap: wrap; gap: 8px; }
.chip {
  display: inline-block;
  padding: 4px 11px;
  border-radius: 999px;
  background: var(--surface-2);
  color: var(--muted);
  font-size: 13px;
  font-weight: 600;
}

/* ---------- sections ---------- */
.lesson-section { margin-top: 44px; }
.sec-head {
  display: flex;
  align-items: center;
  gap: 14px;
  margin-bottom: 14px;
}
.sec-num {
  flex: 0 0 auto;
  width: 34px;
  height: 34px;
  border-radius: 10px;
  display: grid;
  place-items: center;
  background: var(--accent);
  color: var(--accent-text);
  font-weight: 700;
  font-size: 15px;
}
.sec-head h3 {
  margin: 0;
  font-size: 22px;
  line-height: 1.3;
  letter-spacing: -0.005em;
}
.lecture p { margin: 10px 0 12px; color: var(--text); }

/* subsections */
.sub { margin: 18px 0 8px; }
.sub > h4 { font-size: 17px; margin: 0 0 6px; letter-spacing: -0.005em; }
.sub-concept {
  padding-left: 14px;
  border-left: 3px solid var(--border);
}

/* worked-example steps */
.sub-step {
  display: grid;
  grid-template-columns: 34px minmax(0, 1fr);
  gap: 14px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 14px 16px;
  margin: 14px 0;
  box-shadow: var(--shadow);
}
.step-badge {
  width: 30px;
  height: 30px;
  border-radius: 999px;
  display: grid;
  place-items: center;
  background: var(--surface-2);
  color: var(--accent);
  font-weight: 700;
  font-size: 14px;
  border: 1px solid var(--border);
}
.step-body h4 { margin: 2px 0 6px; font-size: 16px; }
.step-body p, .step-body li { font-size: 16px; }

/* common mistakes */
.sub-mistake {
  background: var(--surface);
  border: 1px solid var(--border);
  border-left: 4px solid var(--bad);
  border-radius: 14px;
  padding: 14px 18px;
  margin: 16px 0;
  box-shadow: var(--shadow);
}
.sub-mistake > h4 { margin: 0 0 8px; font-size: 16px; }
.mistake-tag {
  display: inline-block;
  font-size: 11.5px;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--bad);
  background: var(--bad-bg);
  padding: 2px 8px;
  border-radius: 6px;
  margin-right: 6px;
  vertical-align: 2px;
}

/* key-value lines inside cards: "Why it is a problem: ..." */
.kv { margin: 6px 0; }
.kv-key {
  display: inline-block;
  min-width: 150px;
  font-size: 12.5px;
  font-weight: 700;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.04em;
}
.sub-mistake .kv-key { color: var(--text); }

/* callouts */
.callout {
  margin: 16px 0;
  padding: 12px 16px 12px 18px;
  border-radius: 12px;
  border: 1px solid var(--border);
  border-left: 4px solid var(--accent);
  background: var(--surface);
  font-size: 15.5px;
  line-height: 1.6;
}
.callout strong { color: var(--text); }
.callout-note { border-left-color: var(--accent); }
.callout-tip { border-left-color: var(--ok); }
.callout-warn { border-left-color: #d97706; }

/* lists */
.lecture ul, .lecture ol { margin: 8px 0 14px; padding-left: 22px; }
.lecture li { margin: 6px 0; }

.lecture-checklist-block {
  margin: 16px 0 22px;
  padding: 14px 16px 16px;
  border-radius: 16px;
  border: 1px solid color-mix(in srgb, #22c55e 30%, var(--border));
  background: linear-gradient(
    165deg,
    color-mix(in srgb, #22c55e 8%, var(--surface)),
    color-mix(in srgb, #22c55e 3%, var(--surface-2))
  );
  box-shadow: 0 12px 28px -20px color-mix(in srgb, #22c55e 35%, transparent);
}
.lecture-checklist__heading {
  margin: 0 0 10px;
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 0.07em;
  text-transform: uppercase;
  color: #15803d;
}
[data-theme="dark"] .lecture-checklist__heading {
  color: #86efac;
}
.lecture-checklist {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 8px;
}
.lecture-checklist li {
  position: relative;
  margin: 0;
  padding: 11px 12px 11px 38px;
  border-radius: 12px;
  background: var(--surface);
  border: 1px solid color-mix(in srgb, var(--border) 90%, transparent);
  font-size: 15px;
  line-height: 1.5;
  font-weight: 600;
  color: var(--text);
}
.lecture-checklist li::before {
  content: "✓";
  position: absolute;
  left: 12px;
  top: 11px;
  width: 20px;
  height: 20px;
  border-radius: 6px;
  display: grid;
  place-items: center;
  font-size: 12px;
  font-weight: 800;
  color: #fff;
  background: linear-gradient(135deg, #22c55e, #16a34a);
  box-shadow: 0 4px 10px -6px rgba(22, 163, 74, 0.8);
}
.lecture-checklist--ordered {
  counter-reset: chk;
}
.lecture-checklist--ordered li {
  counter-increment: chk;
  padding-left: 42px;
}
.lecture-checklist--ordered li::before {
  content: counter(chk);
  font-size: 11px;
}
.lecture-checklist__status {
  display: inline-block;
  margin-left: 8px;
  padding: 2px 8px;
  border-radius: 999px;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  vertical-align: middle;
  background: var(--surface-2);
  color: var(--muted);
}
.lecture-checklist__status--yes,
.lecture-checklist__status--met {
  background: #dcfce7;
  color: #15803d;
}
.lecture-checklist__status--pending {
  background: #fef3c7;
  color: #b45309;
}
.lecture-checklist-block--table .table-card--checklist {
  margin: 0;
  border: 0;
  box-shadow: none;
  background: transparent;
}
.lecture-checklist-block--table .table-card--checklist .grid-table td.id,
.lecture-checklist-block--table .table-card--checklist .grid-table th:first-child {
  font-weight: 800;
  color: var(--accent);
}
.workflow-step__checklist {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 6px;
}
.workflow-step__checklist li {
  position: relative;
  padding-left: 22px;
  font-size: 13px;
  line-height: 1.45;
  font-weight: 600;
  color: var(--muted);
}
.workflow-step__checklist li::before {
  content: "•";
  position: absolute;
  left: 6px;
  top: 0;
  color: var(--workflow-icon-fg, var(--accent));
  font-weight: 900;
  font-size: 14px;
}

/* SDLC × STLC dual-track diagram (Lecture 5) */
.lifecycle-diagram__intro {
  text-align: center;
  max-width: 40rem;
  margin: 0 auto 18px;
}
.lifecycle-diagram__badge {
  display: inline-block;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: #4338ca;
  background: linear-gradient(135deg, #e0e7ff, #ede9fe);
  padding: 5px 12px;
  border-radius: 999px;
  margin-bottom: 10px;
}
.lifecycle-diagram__title {
  margin: 0 0 8px;
  font-size: clamp(1.2rem, 2.5vw, 1.45rem);
  font-weight: 800;
  color: var(--heading);
}
.lifecycle-diagram__subtitle {
  margin: 0;
  font-size: 14px;
  line-height: 1.5;
  color: var(--muted);
}
.lifecycle-diagram__board {
  padding: 14px 12px 16px;
  border-radius: 16px;
  border: 1px solid var(--border);
  background: linear-gradient(180deg, var(--surface-2) 0%, var(--surface) 100%);
  overflow-x: auto;
}
.lifecycle-diagram__legend {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 10px 16px;
  margin-bottom: 12px;
}
.lifecycle-diagram__legend-item {
  font-size: 11px;
  font-weight: 800;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  padding: 5px 10px;
  border-radius: 8px;
}
.lifecycle-diagram__legend-item--sdlc {
  color: #1d4ed8;
  background: color-mix(in srgb, #dbeafe 70%, var(--surface));
}
.lifecycle-diagram__legend-item--stlc {
  color: #047857;
  background: color-mix(in srgb, #d1fae5 70%, var(--surface));
}
.lifecycle-diagram__track {
  display: flex;
  align-items: stretch;
  gap: 4px;
  min-width: 680px;
}
.lifecycle-diagram__col {
  flex: 1 1 0;
  min-width: 96px;
  display: flex;
  flex-direction: column;
  align-items: stretch;
}
.lifecycle-diagram__phase {
  position: relative;
  padding: 12px 10px 12px 34px;
  border-radius: 12px;
  border: 1px solid var(--border);
  min-height: 64px;
  display: flex;
  align-items: center;
  box-shadow: 0 8px 20px -14px rgba(37, 36, 80, 0.35);
}
.lifecycle-diagram__phase--sdlc {
  background: linear-gradient(165deg, #eff6ff, var(--surface));
  border-top: 3px solid #3b82f6;
}
.lifecycle-diagram__phase--stlc {
  background: linear-gradient(165deg, #ecfdf5, var(--surface));
  border-top: 3px solid #10b981;
}
.lifecycle-diagram__phase-num {
  position: absolute;
  left: 8px;
  top: 50%;
  transform: translateY(-50%);
  width: 22px;
  height: 22px;
  border-radius: 7px;
  display: grid;
  place-items: center;
  font-size: 11px;
  font-weight: 800;
  color: #fff;
}
.lifecycle-diagram__phase--sdlc .lifecycle-diagram__phase-num {
  background: #3b82f6;
}
.lifecycle-diagram__phase--stlc .lifecycle-diagram__phase-num {
  background: #10b981;
}
.lifecycle-diagram__phase-name {
  font-size: 12.5px;
  line-height: 1.35;
  font-weight: 700;
  color: var(--heading);
}
.lifecycle-diagram__vlink {
  flex: 0 0 auto;
  display: flex;
  justify-content: center;
  padding: 4px 0;
}
.lifecycle-diagram__vlink span {
  display: block;
  width: 2px;
  height: 18px;
  border-radius: 2px;
  background: linear-gradient(180deg, #3b82f6, #10b981);
}
.lifecycle-diagram__harrow {
  flex: 0 0 20px;
  display: flex;
  align-items: center;
  align-self: center;
  color: #93c5fd;
  padding-top: 28px;
}
.lifecycle-diagram__harrow svg {
  width: 20px;
  height: 20px;
}
.lifecycle-diagram__footnote {
  margin: 12px 4px 0;
  text-align: center;
  font-size: 12.5px;
  line-height: 1.45;
  color: var(--muted);
}
@media (max-width: 720px) {
  .lifecycle-diagram__phase-name {
    font-size: 11.5px;
  }
}

/* SDLC × STLC relationship / overlap (Lecture 5 §3.3) */
.cycles-relate__intro {
  text-align: center;
  max-width: 40rem;
  margin: 0 auto 16px;
}
.cycles-relate__badge {
  display: inline-block;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: #7c3aed;
  background: linear-gradient(135deg, #ede9fe, #e0e7ff);
  padding: 5px 12px;
  border-radius: 999px;
  margin-bottom: 10px;
}
.cycles-relate__title {
  margin: 0 0 8px;
  font-size: clamp(1.15rem, 2.4vw, 1.4rem);
  font-weight: 800;
  color: var(--heading);
}
.cycles-relate__subtitle {
  margin: 0;
  font-size: 14px;
  line-height: 1.5;
  color: var(--muted);
}
.cycles-relate__panel {
  margin-bottom: 12px;
  padding: 14px 14px 16px;
  border-radius: 14px;
  border: 1px solid var(--border);
}
.cycles-relate__panel--myth {
  background: color-mix(in srgb, #fef2f2 50%, var(--surface));
  border-color: color-mix(in srgb, #f87171 35%, var(--border));
}
.cycles-relate__panel--reality {
  background: color-mix(in srgb, #ecfdf5 45%, var(--surface));
  border-color: color-mix(in srgb, #34d399 35%, var(--border));
}
.cycles-relate__panel-title {
  margin: 0 0 4px;
  font-size: 11px;
  font-weight: 800;
  letter-spacing: 0.07em;
  text-transform: uppercase;
  color: var(--muted);
}
.cycles-relate__panel--myth .cycles-relate__panel-title {
  color: #b91c1c;
}
.cycles-relate__panel--reality .cycles-relate__panel-title {
  color: #047857;
}
.cycles-relate__panel-lead {
  margin: 0 0 12px;
  font-size: 14px;
  font-weight: 700;
  color: var(--heading);
}
.cycles-relate__sequential {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
  justify-content: center;
}
.cycles-relate__seq-block {
  flex: 1 1 120px;
  max-width: 200px;
  padding: 12px 14px;
  border-radius: 12px;
  border: 1px dashed var(--border);
  text-align: center;
}
.cycles-relate__seq-block span {
  display: block;
  font-weight: 800;
  font-size: 14px;
}
.cycles-relate__seq-block small {
  display: block;
  margin-top: 4px;
  font-size: 11px;
  color: var(--muted);
}
.cycles-relate__seq-block--sdlc {
  background: color-mix(in srgb, #dbeafe 50%, var(--surface));
}
.cycles-relate__seq-block--stlc {
  background: color-mix(in srgb, #d1fae5 50%, var(--surface));
}
.cycles-relate__seq-arrow {
  font-size: 12px;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: #b91c1c;
}
.cycles-relate__timeline {
  overflow-x: auto;
  padding-bottom: 4px;
}
.cycles-relate__row {
  display: flex;
  align-items: center;
  gap: 10px;
  min-width: 520px;
  margin-bottom: 8px;
}
.cycles-relate__row-label {
  flex: 0 0 52px;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  text-align: right;
  color: var(--muted);
}
.cycles-relate__row--sdlc .cycles-relate__row-label {
  color: #1d4ed8;
}
.cycles-relate__row--stlc .cycles-relate__row-label {
  color: #047857;
}
.cycles-relate__bar {
  flex: 1;
  display: flex;
  gap: 3px;
  min-height: 44px;
}
.cycles-relate__seg {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 6px 4px;
  border-radius: 8px;
  font-size: 10px;
  font-weight: 700;
  line-height: 1.25;
  text-align: center;
  color: var(--heading);
  border: 1px solid color-mix(in srgb, var(--border) 80%, transparent);
}
.cycles-relate__row--sdlc .cycles-relate__seg {
  background: linear-gradient(180deg, #eff6ff, #dbeafe);
}
.cycles-relate__row--stlc .cycles-relate__seg {
  background: linear-gradient(180deg, #ecfdf5, #d1fae5);
}
.cycles-relate__overlap {
  margin: 4px 0 10px 62px;
  padding: 8px 12px;
  border-radius: 10px;
  background: linear-gradient(
    90deg,
    color-mix(in srgb, #8b5cf6 12%, transparent),
    color-mix(in srgb, #22c55e 14%, transparent)
  );
  border: 1px dashed color-mix(in srgb, #8b5cf6 35%, var(--border));
}
.cycles-relate__overlap-label {
  font-size: 11px;
  font-weight: 700;
  color: #5b21b6;
}
[data-theme="dark"] .cycles-relate__overlap-label {
  color: #c4b5fd;
}
.cycles-relate__callouts {
  list-style: none;
  margin: 14px 0 0;
  padding: 0;
  display: grid;
  gap: 8px;
}
.cycles-relate__callouts li {
  position: relative;
  margin: 0;
  padding: 10px 12px 10px 34px;
  border-radius: 10px;
  background: var(--surface);
  border: 1px solid var(--border);
  font-size: 14px;
  line-height: 1.45;
  font-weight: 600;
  color: var(--text);
}
.cycles-relate__callouts li::before {
  content: "↔";
  position: absolute;
  left: 12px;
  top: 10px;
  font-weight: 800;
  color: var(--accent);
}
.cycles-relate__footnote {
  margin: 12px 0 0;
  text-align: center;
  font-size: 12.5px;
  color: var(--muted);
}
.objectives {
  list-style: none;
  padding-left: 0;
  counter-reset: obj;
  display: grid;
  gap: 8px;
}
.objectives li {
  counter-increment: obj;
  position: relative;
  padding: 10px 14px 10px 50px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  margin: 0;
}
.objectives li::before {
  content: counter(obj);
  position: absolute;
  left: 14px;
  top: 10px;
  width: 24px;
  height: 24px;
  border-radius: 8px;
  display: grid;
  place-items: center;
  background: var(--accent);
  color: var(--accent-text);
  font-size: 12.5px;
  font-weight: 700;
}
.steps-list li { margin: 6px 0; }

/* tables */
.table-card {
  overflow-x: auto;
  margin: 12px 0 22px;
  border: 1px solid var(--border);
  border-radius: 14px;
  background: var(--surface);
  box-shadow: var(--shadow);
}
.lecture .grid-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 14.5px;
  line-height: 1.5;
}
.lecture .grid-table th,
.lecture .grid-table td {
  padding: 10px 14px;
  text-align: left;
  vertical-align: top;
  border-bottom: 1px solid var(--border);
}
.lecture .grid-table th {
  background: var(--surface-2);
  font-size: 12.5px;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--muted);
}
.lecture .grid-table tr:last-child td { border-bottom: 0; }
.lecture .grid-table td.id {
  white-space: nowrap;
  font-weight: 700;
  color: var(--accent);
}
.caption {
  margin: 18px 0 2px;
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.03em;
  color: var(--muted);
}

/* code */
.lecture code {
  font: 13.5px ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  background: var(--surface-2);
  padding: 1px 6px;
  border-radius: 6px;
}
.code-card {
  margin: 14px 0 20px;
  border: 1px solid var(--border);
  border-radius: 14px;
  background: var(--surface-2);
  overflow: hidden;
}
.code-card pre {
  margin: 0;
  padding: 14px 16px;
  overflow-x: auto;
}
.code-card code { background: none; padding: 0; font-size: 13.5px; line-height: 1.6; }

.code-card--terminal {
  margin: 18px 0 22px;
  border: 1px solid color-mix(in srgb, #22c55e 35%, var(--border));
  border-radius: 16px;
  background: linear-gradient(165deg, #0f172a 0%, #1e293b 100%);
  box-shadow:
    0 16px 36px -20px rgba(15, 23, 42, 0.65),
    inset 0 1px 0 rgba(255, 255, 255, 0.06);
}
[data-theme="dark"] .code-card--terminal {
  border-color: color-mix(in srgb, #4ade80 40%, var(--border));
}
.code-card__label {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 10px 14px;
  font-size: 11px;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: #86efac;
  background: rgba(0, 0, 0, 0.25);
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
}
.code-card__label-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 22px;
  height: 22px;
  border-radius: 6px;
  font-size: 12px;
  background: rgba(34, 197, 94, 0.2);
  color: #bbf7d0;
}
.code-card__label-text {
  color: #bbf7d0;
}
.code-card--terminal pre {
  padding: 16px 18px 18px;
}
.code-card--terminal .code-card__command {
  font-size: 15.5px;
  line-height: 1.65;
  font-weight: 600;
  color: #e2e8f0;
  letter-spacing: 0.01em;
}
.step .code-card--terminal {
  margin: 16px 0 20px;
}
.lecture-inline-cmd {
  font-size: 14px !important;
  font-weight: 700 !important;
  padding: 3px 9px !important;
  border-radius: 8px !important;
  background: color-mix(in srgb, #22c55e 12%, var(--surface-2)) !important;
  border: 1px solid color-mix(in srgb, #22c55e 35%, var(--border));
  color: var(--heading) !important;
}

/* visuals — diagrams and lecture images */
.visual {
  margin: 28px 0 32px;
  max-width: 100%;
}
.visual-frame {
  position: relative;
  background: linear-gradient(165deg, var(--surface) 0%, var(--surface-2) 100%);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 0;
  box-shadow: var(--shadow-lift);
  overflow: hidden;
}
.visual-frame::before {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: inherit;
  padding: 1px;
  background: var(--brand-gradient);
  -webkit-mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
  mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
  -webkit-mask-composite: xor;
  mask-composite: exclude;
  pointer-events: none;
  opacity: 0.35;
}
.visual-header {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px 12px;
  padding: 14px 18px 10px;
  border-bottom: 1px solid var(--border);
  background: rgba(255, 255, 255, 0.55);
}
[data-theme="dark"] .visual-header {
  background: rgba(20, 22, 40, 0.45);
}
.visual-badge {
  flex: 0 0 auto;
  font-size: 11px;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent-text);
  background: var(--brand-gradient);
  padding: 4px 10px;
  border-radius: 999px;
  box-shadow: 0 6px 16px -8px rgba(79, 70, 229, 0.65);
}
.visual-kicker {
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--muted);
}
.visual-title {
  flex: 1 1 180px;
  font-size: 15px;
  font-weight: 700;
  color: var(--heading);
  line-height: 1.35;
}
.visual-canvas {
  padding: 12px 10px 16px;
  background:
    radial-gradient(circle at 12% 8%, rgba(98, 84, 232, 0.06), transparent 42%),
    radial-gradient(circle at 88% 92%, rgba(71, 120, 232, 0.07), transparent 40%);
}
.visual-canvas--photo {
  padding: 0;
  background: var(--surface-2);
}
.visual .diagram {
  display: block;
  width: 100%;
  height: auto;
  min-width: 0;
}
.visual-canvas .diagram .diagram-node {
  filter: drop-shadow(0 5px 14px rgba(37, 36, 80, 0.1));
}
.visual-photo {
  display: block;
  width: 100%;
  max-height: min(420px, 56vh);
  object-fit: cover;
  object-position: center;
}
.visual-caption {
  margin: 12px 4px 0;
  padding-left: 14px;
  border-left: 3px solid var(--accent);
  text-align: left;
}
.visual-caption__title {
  display: block;
  font-size: 14px;
  font-weight: 800;
  color: var(--heading);
  margin-bottom: 4px;
}
.visual-caption__text {
  margin: 0;
  font-size: 14.5px;
  line-height: 1.55;
  color: var(--muted);
}
.visual-caption__text:last-child {
  margin-bottom: 0;
}

/* Workflow board pattern (card steps + arrows) */
.visual--workflow .visual-header {
  padding-bottom: 8px;
}
.visual-canvas--workflow {
  padding: 20px 18px 24px;
}
.workflow-board__intro {
  text-align: center;
  max-width: 36rem;
  margin: 0 auto 22px;
}
.workflow-board__badge {
  display: inline-block;
  font-size: 11px;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: #5b21b6;
  background: linear-gradient(135deg, #ede9fe, #e0e7ff);
  padding: 5px 12px;
  border-radius: 999px;
  margin-bottom: 10px;
}
[data-theme="dark"] .workflow-board__badge {
  color: #c4b5fd;
  background: linear-gradient(135deg, rgba(91, 33, 182, 0.35), rgba(79, 70, 229, 0.25));
}
.workflow-board__title {
  margin: 0 0 8px;
  font-size: clamp(1.35rem, 2.8vw, 1.75rem);
  font-weight: 800;
  letter-spacing: -0.02em;
  color: var(--heading);
  line-height: 1.2;
}
.workflow-board__subtitle {
  margin: 0;
  font-size: 14px;
  line-height: 1.5;
  color: var(--muted);
}
.workflow-board__flow {
  display: flex;
  flex-direction: column;
  gap: 18px;
}
.workflow-board__row {
  display: flex;
  align-items: stretch;
  justify-content: center;
  flex-wrap: wrap;
  gap: 10px 6px;
}
.workflow-board__row--tail {
  justify-content: flex-start;
  max-width: min(100%, 640px);
  margin: 0 auto;
  padding-left: clamp(0px, 4vw, 12px);
}
.workflow-arrow {
  flex: 0 0 auto;
  display: flex;
  align-items: center;
  align-self: center;
  width: 36px;
  color: #93c5fd;
  opacity: 0.95;
}
.workflow-arrow svg {
  display: block;
  width: 100%;
  height: auto;
}
.workflow-step {
  position: relative;
  flex: 1 1 168px;
  max-width: 220px;
  min-width: 150px;
  padding: 14px 14px 16px 18px;
  border-radius: 16px;
  background: var(--surface);
  border: 1px solid color-mix(in srgb, var(--border) 85%, transparent);
  box-shadow: 0 12px 28px -18px rgba(37, 36, 80, 0.35);
  overflow: hidden;
}
.workflow-step__accent {
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 5px;
  border-radius: 16px 0 0 16px;
  background: var(--workflow-accent, #3b82f6);
}
.workflow-step--blue { --workflow-accent: #3b82f6; --workflow-icon-bg: #dbeafe; --workflow-icon-fg: #2563eb; --workflow-num-bg: #3b82f6; }
.workflow-step--green { --workflow-accent: #22c55e; --workflow-icon-bg: #dcfce7; --workflow-icon-fg: #16a34a; --workflow-num-bg: #22c55e; }
.workflow-step--purple { --workflow-accent: #8b5cf6; --workflow-icon-bg: #ede9fe; --workflow-icon-fg: #7c3aed; --workflow-num-bg: #8b5cf6; }
.workflow-step--rose { --workflow-accent: #f43f5e; --workflow-icon-bg: #ffe4e6; --workflow-icon-fg: #e11d48; --workflow-num-bg: #f43f5e; }
.workflow-step--teal { --workflow-accent: #14b8a6; --workflow-icon-bg: #ccfbf1; --workflow-icon-fg: #0d9488; --workflow-num-bg: #14b8a6; }
[data-theme="dark"] .workflow-step--blue { --workflow-icon-bg: rgba(59, 130, 246, 0.2); }
[data-theme="dark"] .workflow-step--green { --workflow-icon-bg: rgba(34, 197, 94, 0.18); }
[data-theme="dark"] .workflow-step--purple { --workflow-icon-bg: rgba(139, 92, 246, 0.22); }
[data-theme="dark"] .workflow-step--rose { --workflow-icon-bg: rgba(244, 63, 94, 0.2); }
[data-theme="dark"] .workflow-step--teal { --workflow-icon-bg: rgba(20, 184, 166, 0.2); }
.workflow-step__icon {
  width: 40px;
  height: 40px;
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 10px;
  color: var(--workflow-icon-fg);
  background: var(--workflow-icon-bg);
}
.workflow-step__icon svg {
  width: 22px;
  height: 22px;
}
.workflow-step__num {
  position: absolute;
  top: 12px;
  right: 12px;
  width: 26px;
  height: 26px;
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 12px;
  font-weight: 800;
  color: #fff;
  background: var(--workflow-num-bg);
  box-shadow: 0 4px 10px -4px color-mix(in srgb, var(--workflow-num-bg) 80%, transparent);
}
.workflow-step__title {
  margin: 0 0 6px;
  font-size: 15px;
  font-weight: 800;
  color: var(--heading);
  line-height: 1.3;
  padding-right: 28px;
}
.workflow-step__link {
  color: inherit;
  text-decoration: none;
  border-bottom: 1px solid color-mix(in srgb, var(--workflow-accent, var(--accent)) 45%, transparent);
  transition: color 0.15s ease, border-color 0.15s ease;
}
.workflow-step__link:hover {
  color: var(--workflow-icon-fg, var(--accent));
  border-bottom-color: currentColor;
}
.workflow-step__link:focus-visible {
  outline: 2px solid var(--workflow-icon-fg, var(--accent));
  outline-offset: 2px;
  border-radius: 4px;
}
.workflow-step__link-ext {
  display: inline-block;
  margin-left: 3px;
  font-size: 11px;
  font-weight: 700;
  opacity: 0.75;
}
.workflow-step__desc {
  margin: 0;
  font-size: 14px;
  line-height: 1.45;
  color: var(--muted);
}
@media (max-width: 720px) {
  .workflow-board__row--tail {
    padding-left: 0;
    justify-content: center;
  }
  .workflow-arrow {
    display: none;
  }
  .workflow-board__row {
    flex-direction: column;
    align-items: center;
  }
  .workflow-step {
    max-width: 100%;
    width: min(100%, 320px);
  }
}

/* Application under test (AUT) mock screens */
.visual--app .visual-header {
  padding-bottom: 8px;
}
.visual-canvas--app {
  padding: 18px 16px 22px;
}
.app-mock__badge {
  margin: 0 0 12px;
  text-align: center;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: #0369a1;
}
.app-mock__shell {
  max-width: 520px;
  margin: 0 auto;
  border-radius: 16px;
  border: 1px solid var(--border);
  background: var(--surface);
  box-shadow: 0 20px 40px -24px rgba(37, 36, 80, 0.45);
  overflow: hidden;
}
.app-mock__toolbar {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 12px;
  background: color-mix(in srgb, var(--surface-2) 90%, var(--border));
  border-bottom: 1px solid var(--border);
  font-size: 11px;
}
.app-mock__window-controls {
  display: flex;
  gap: 5px;
  flex-shrink: 0;
}
.app-mock__dot {
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--border);
}
.app-mock__dot--close { background: #f87171; }
.app-mock__dot--min { background: #fbbf24; }
.app-mock__dot--max { background: #4ade80; }
.app-mock__url {
  flex: 1;
  min-width: 0;
  padding: 5px 10px;
  border-radius: 8px;
  background: var(--surface);
  border: 1px solid var(--border);
  color: var(--muted);
  font-weight: 600;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.app-mock__env {
  flex-shrink: 0;
  font-weight: 800;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  font-size: 9px;
  color: #0d9488;
  background: #ccfbf1;
  padding: 4px 8px;
  border-radius: 6px;
}
[data-theme="dark"] .app-mock__env {
  color: #5eead4;
  background: rgba(20, 184, 166, 0.2);
}
.app-mock__body {
  padding: 20px 22px 24px;
  background: linear-gradient(180deg, #f8fafc 0%, var(--surface) 42%);
}
[data-theme="dark"] .app-mock__body {
  background: linear-gradient(180deg, rgba(30, 32, 55, 0.6) 0%, var(--surface) 50%);
}
.app-mock__brand {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 8px 12px;
  margin-bottom: 16px;
}
.app-mock__logo {
  font-size: 1.35rem;
  font-weight: 800;
  letter-spacing: -0.03em;
  color: #4f46e5;
}
.app-mock__tagline {
  font-size: 12px;
  font-weight: 600;
  color: var(--muted);
}
.app-mock__panel {
  padding: 18px 18px 20px;
  border-radius: 14px;
  border: 1px solid var(--border);
  background: var(--surface);
  box-shadow: 0 8px 24px -16px rgba(37, 36, 80, 0.25);
}
.app-mock__screen-title {
  margin: 0 0 4px;
  font-size: 1.1rem;
  font-weight: 800;
  color: var(--heading);
}
.app-mock__req {
  margin: 0 0 14px;
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--accent);
}
.app-mock__field {
  margin-bottom: 12px;
}
.app-mock__label {
  display: block;
  font-size: 11px;
  font-weight: 700;
  color: var(--muted);
  margin-bottom: 4px;
}
.app-mock__input {
  padding: 10px 12px;
  border-radius: 10px;
  border: 1px solid var(--border);
  background: var(--surface-2);
  font-size: 13px;
  font-weight: 600;
  color: var(--text);
}
.app-mock__field--ok .app-mock__input {
  border-color: color-mix(in srgb, #22c55e 55%, var(--border));
  background: color-mix(in srgb, #dcfce7 40%, var(--surface-2));
}
.app-mock__field--error .app-mock__input {
  border-color: color-mix(in srgb, #f43f5e 55%, var(--border));
  background: color-mix(in srgb, #ffe4e6 35%, var(--surface-2));
}
.app-mock__hint {
  margin: 5px 0 0;
  font-size: 11px;
  color: var(--muted);
  line-height: 1.35;
}
.app-mock__cta {
  display: block;
  width: 100%;
  margin-top: 6px;
  padding: 11px 14px;
  border: 0;
  border-radius: 10px;
  font-size: 14px;
  font-weight: 800;
  color: #fff;
  background: linear-gradient(135deg, #6366f1, #4f46e5);
  box-shadow: 0 8px 18px -10px rgba(79, 70, 229, 0.8);
  cursor: default;
}
.app-mock__footnote {
  margin: 12px 0 0;
  font-size: 11.5px;
  line-height: 1.45;
  color: var(--muted);
  text-align: center;
}
.app-mock__intro {
  margin: 0 0 14px;
  font-size: 12.5px;
  line-height: 1.45;
  color: var(--muted);
  text-align: center;
}
.app-mock__secondary {
  margin: 10px 0 0;
  font-size: 12px;
  font-weight: 600;
  text-align: center;
  color: #4f46e5;
}
[data-theme="dark"] .app-mock__secondary {
  color: #a5b4fc;
}
.app-mock__flow {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: center;
  gap: 6px 4px;
  margin-top: 14px;
  padding: 10px 12px;
  border-radius: 10px;
  background: var(--surface-2, rgba(99, 102, 241, 0.06));
  border: 1px dashed rgba(99, 102, 241, 0.35);
}
.app-mock__flow-step {
  padding: 4px 10px;
  font-size: 11px;
  font-weight: 700;
  line-height: 1.3;
  color: var(--text);
  background: var(--card-bg, #fff);
  border-radius: 999px;
  border: 1px solid rgba(99, 102, 241, 0.25);
}
.app-mock__flow-arrow {
  font-size: 12px;
  font-weight: 800;
  color: var(--muted);
}
.app-mock__summary {
  margin: 0 0 14px;
  padding: 12px 14px;
  border-radius: 12px;
  background: var(--surface-2);
  border: 1px solid var(--border);
}
.app-mock__summary-row {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 12px;
  padding: 5px 0;
  font-size: 12.5px;
  border-bottom: 1px dashed color-mix(in srgb, var(--border) 80%, transparent);
}
.app-mock__summary-row:last-child {
  border-bottom: none;
}
.app-mock__summary-label {
  color: var(--muted);
  font-weight: 600;
}
.app-mock__summary-value {
  font-weight: 800;
  color: var(--heading);
}
.app-mock__summary-row--discount .app-mock__summary-value {
  color: #059669;
}
.app-mock__summary-row--ok .app-mock__summary-value {
  color: #4f46e5;
}

/* Lecture 6 — discount roles intro */
.discount-roles__badge {
  margin: 0 0 14px;
  text-align: center;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: #b45309;
}
.discount-roles__grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
  max-width: 720px;
  margin: 0 auto;
}
.discount-roles__card {
  padding: 14px 14px 16px;
  border-radius: 14px;
  border: 1px solid var(--border);
  background: var(--surface);
  box-shadow: 0 12px 28px -22px rgba(37, 36, 80, 0.45);
}
.discount-roles__card--dev {
  border-top: 4px solid #3b82f6;
}
.discount-roles__card--qc {
  border-top: 4px solid #8b5cf6;
}
.discount-roles__card--val {
  border-top: 4px solid #10b981;
}
.discount-roles__role {
  display: block;
  margin-bottom: 8px;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--muted);
}
.discount-roles__question {
  margin: 0 0 8px;
  font-size: 13px;
  font-weight: 800;
  line-height: 1.35;
  color: var(--heading);
}
.discount-roles__activity {
  margin: 0;
  font-size: 12px;
  line-height: 1.45;
  color: var(--muted);
}
.discount-roles__lesson {
  margin: 14px auto 0;
  max-width: 40rem;
  text-align: center;
  font-size: 13px;
  line-height: 1.5;
  color: var(--muted);
}
@media (max-width: 720px) {
  .discount-roles__grid {
    grid-template-columns: 1fr;
  }
}

/* Lecture 6 — 2×2 terms matrix */
.terms-matrix__intro {
  text-align: center;
  max-width: 40rem;
  margin: 0 auto 16px;
}
.terms-matrix__badge {
  display: inline-block;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: #4f46e5;
  background: linear-gradient(135deg, #eef2ff, #e0e7ff);
  padding: 5px 12px;
  border-radius: 999px;
  margin-bottom: 10px;
}
.terms-matrix__title {
  margin: 0 0 8px;
  font-size: clamp(1.2rem, 2.4vw, 1.5rem);
  font-weight: 800;
  color: var(--heading);
}
.terms-matrix__subtitle {
  margin: 0;
  font-size: 15.5px;
  line-height: 1.5;
  color: var(--muted);
}
.terms-matrix__board {
  max-width: 720px;
  margin: 0 auto;
  border-radius: 14px;
  border: 1px solid var(--border);
  overflow: hidden;
  background: var(--surface);
}
.terms-matrix__colhead {
  display: grid;
  grid-template-columns: 124px 1fr 1fr;
  gap: 0;
  border-bottom: 1px solid var(--border);
  background: var(--surface-2);
}
.terms-matrix__corner {
  border-right: 1px solid var(--border);
}
.terms-matrix__colhead-cell {
  padding: 12px 14px;
  text-align: center;
  border-left: 1px solid var(--border);
}
.terms-matrix__colhead-cell strong {
  display: block;
  font-size: 14.5px;
  font-weight: 800;
  color: var(--heading);
}
.terms-matrix__colhead-cell small {
  display: block;
  margin-top: 3px;
  font-size: 12.5px;
  color: var(--muted);
  font-weight: 600;
}
.terms-matrix__colhead-cell--verify strong {
  color: #2563eb;
}
.terms-matrix__colhead-cell--validate strong {
  color: #059669;
}
.terms-matrix__row {
  display: grid;
  grid-template-columns: 124px 1fr 1fr;
  border-bottom: 1px solid var(--border);
}
.terms-matrix__row:last-child {
  border-bottom: none;
}
.terms-matrix__rowhead {
  padding: 14px 12px;
  border-right: 1px solid var(--border);
  background: color-mix(in srgb, var(--surface-2) 70%, var(--surface));
}
.terms-matrix__rowhead strong {
  display: block;
  font-size: 15px;
  font-weight: 800;
  color: var(--heading);
}
.terms-matrix__rowhead small {
  display: block;
  margin-top: 3px;
  font-size: 12px;
  font-weight: 700;
  color: var(--muted);
}
.terms-matrix__row--qa .terms-matrix__rowhead {
  border-left: 4px solid #6366f1;
}
.terms-matrix__row--qc .terms-matrix__rowhead {
  border-left: 4px solid #a855f7;
}
.terms-matrix__cell {
  padding: 14px 14px;
  font-size: 14px;
  line-height: 1.5;
  color: var(--text);
  border-left: 1px solid var(--border);
}
.terms-matrix__cell--verify {
  background: color-mix(in srgb, #eff6ff 35%, var(--surface));
}
.terms-matrix__cell--validate {
  background: color-mix(in srgb, #ecfdf5 35%, var(--surface));
}
.terms-matrix__footnote {
  margin: 12px 4px 0;
  text-align: center;
  font-size: 14px;
  line-height: 1.5;
  color: var(--muted);
}
@media (max-width: 640px) {
  .terms-matrix__colhead,
  .terms-matrix__row {
    grid-template-columns: 1fr;
  }
  .terms-matrix__corner {
    display: none;
  }
  .terms-matrix__rowhead {
    border-right: none;
    border-bottom: 1px solid var(--border);
  }
}

/* Lecture 6 — dual pillar compare */
.dual-pillar__intro {
  text-align: center;
  max-width: 40rem;
  margin: 0 auto 16px;
}
.dual-pillar__badge {
  display: inline-block;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: #0d9488;
  background: linear-gradient(135deg, #ccfbf1, #e0f2fe);
  padding: 5px 12px;
  border-radius: 999px;
  margin-bottom: 10px;
}
.dual-pillar__title {
  margin: 0 0 8px;
  font-size: clamp(1.1rem, 2.2vw, 1.35rem);
  font-weight: 800;
  color: var(--heading);
}
.dual-pillar__subtitle {
  margin: 0;
  font-size: 14px;
  line-height: 1.5;
  color: var(--muted);
}
.dual-pillar__grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  max-width: 720px;
  margin: 0 auto;
}
.dual-pillar__col {
  padding: 14px 14px 16px;
  border-radius: 14px;
  border: 1px solid var(--border);
  background: var(--surface);
}
.dual-pillar__col--qa,
.dual-pillar__col--a {
  border-top: 4px solid #6366f1;
}
.dual-pillar__col--qc {
  border-top: 4px solid #a855f7;
}
.dual-pillar__col--verify {
  border-top: 4px solid #3b82f6;
}
.dual-pillar__col--validate {
  border-top: 4px solid #10b981;
}
.dual-pillar__col--b:not(.dual-pillar__col--verify):not(.dual-pillar__col--validate) {
  border-top: 4px solid #14b8a6;
}
.dual-pillar__kicker {
  margin: 0 0 6px;
  font-size: 11px;
  font-weight: 800;
  letter-spacing: 0.07em;
  text-transform: uppercase;
  color: var(--muted);
}
.dual-pillar__headline {
  margin: 0 0 8px;
  font-size: 15px;
  font-weight: 800;
  line-height: 1.35;
  color: var(--heading);
}
.dual-pillar__lead {
  margin: 0 0 10px;
  font-size: 14px;
  line-height: 1.45;
  color: var(--muted);
}
.dual-pillar__list {
  margin: 0;
  padding-left: 1.1rem;
  font-size: 13.5px;
  line-height: 1.45;
  color: var(--text);
}
.dual-pillar__list li {
  margin-bottom: 4px;
}
.dual-pillar__footnote {
  margin: 12px 4px 0;
  text-align: center;
  font-size: 12.5px;
  line-height: 1.45;
  color: var(--muted);
}
@media (max-width: 640px) {
  .dual-pillar__grid {
    grid-template-columns: 1fr;
  }
}

/* Lecture 6 — verification pass vs validation gap */
.verify-gap__intro {
  text-align: center;
  max-width: 40rem;
  margin: 0 auto 16px;
}
.verify-gap__badge {
  display: inline-block;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: #c2410c;
  background: linear-gradient(135deg, #ffedd5, #fef3c7);
  padding: 5px 12px;
  border-radius: 999px;
  margin-bottom: 10px;
}
.verify-gap__title {
  margin: 0 0 8px;
  font-size: clamp(1.1rem, 2.2vw, 1.35rem);
  font-weight: 800;
  color: var(--heading);
}
.verify-gap__subtitle {
  margin: 0;
  font-size: 14px;
  line-height: 1.5;
  color: var(--muted);
}
.verify-gap__split {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 12px;
  align-items: stretch;
  max-width: 720px;
  margin: 0 auto;
}
.verify-gap__arrow {
  display: flex;
  align-items: center;
  font-size: 1.5rem;
  font-weight: 800;
  color: #93c5fd;
  padding-top: 2rem;
}
.verify-gap__panel {
  padding: 14px 14px 16px;
  border-radius: 14px;
  border: 1px solid var(--border);
}
.verify-gap__panel--pass {
  background: color-mix(in srgb, #ecfdf5 45%, var(--surface));
  border-color: color-mix(in srgb, #34d399 35%, var(--border));
}
.verify-gap__panel--gap {
  background: color-mix(in srgb, #fff7ed 50%, var(--surface));
  border-color: color-mix(in srgb, #fb923c 35%, var(--border));
}
.verify-gap__panel-title {
  margin: 0 0 4px;
  font-size: 11px;
  font-weight: 800;
  letter-spacing: 0.07em;
  text-transform: uppercase;
}
.verify-gap__panel--pass .verify-gap__panel-title {
  color: #047857;
}
.verify-gap__panel--gap .verify-gap__panel-title {
  color: #c2410c;
}
.verify-gap__panel-lead {
  margin: 0 0 10px;
  font-size: 13px;
  font-weight: 800;
  line-height: 1.35;
  color: var(--heading);
}
.verify-gap__facts {
  margin: 0;
  padding: 0;
  list-style: none;
  font-size: 12px;
  line-height: 1.45;
}
.verify-gap__facts li {
  display: flex;
  gap: 8px;
  align-items: flex-start;
  margin-bottom: 6px;
}
.verify-gap__tick {
  flex: 0 0 auto;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: #22c55e;
  color: #fff;
  font-size: 11px;
  font-weight: 800;
  display: grid;
  place-items: center;
}
.verify-gap__warn {
  flex: 0 0 auto;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: #f97316;
  color: #fff;
  font-size: 12px;
  font-weight: 800;
  display: grid;
  place-items: center;
}
.verify-gap__fix {
  margin: 10px 0 0;
  padding: 8px 10px;
  border-radius: 10px;
  font-size: 11.5px;
  line-height: 1.45;
  background: color-mix(in srgb, #fef3c7 60%, var(--surface));
  border: 1px solid color-mix(in srgb, #fbbf24 40%, var(--border));
  color: var(--text);
}
.verify-gap__footnote {
  margin: 12px 4px 0;
  text-align: center;
  font-size: 12.5px;
  line-height: 1.45;
  color: var(--muted);
}
@media (max-width: 640px) {
  .verify-gap__split {
    grid-template-columns: 1fr;
  }
  .verify-gap__arrow {
    justify-content: center;
    padding: 0;
    transform: rotate(90deg);
  }
}

/* Lecture 7 — checkout stack intro */
.checkout-stack__badge {
  margin: 0 0 14px;
  text-align: center;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: #b45309;
}
.checkout-stack__flow {
  display: flex;
  flex-wrap: wrap;
  align-items: stretch;
  justify-content: center;
  gap: 8px 6px;
  max-width: 760px;
  margin: 0 auto;
}
.checkout-stack__arrow {
  display: flex;
  align-items: center;
  font-size: 1.25rem;
  font-weight: 800;
  color: #93c5fd;
  padding: 0 2px;
}
.checkout-stack__part {
  flex: 1 1 140px;
  max-width: 168px;
  padding: 12px 12px 14px;
  border-radius: 14px;
  border: 1px solid var(--border);
  background: var(--surface);
  box-shadow: 0 10px 24px -20px rgba(37, 36, 80, 0.45);
}
.checkout-stack__part--unit {
  border-top: 4px solid #3b82f6;
}
.checkout-stack__part--integration {
  border-top: 4px solid #8b5cf6;
}
.checkout-stack__part--system {
  border-top: 4px solid #10b981;
}
.checkout-stack__level {
  display: block;
  margin-bottom: 6px;
  font-size: 9.5px;
  font-weight: 800;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--muted);
}
.checkout-stack__name {
  margin: 0 0 6px;
  font-size: 13px;
  font-weight: 800;
  line-height: 1.3;
  color: var(--heading);
}
.checkout-stack__desc {
  margin: 0;
  font-size: 11.5px;
  line-height: 1.4;
  color: var(--muted);
}
.checkout-stack__lesson {
  margin: 14px auto 0;
  max-width: 40rem;
  text-align: center;
  font-size: 13px;
  line-height: 1.5;
  color: var(--muted);
}
@media (max-width: 720px) {
  .checkout-stack__arrow {
    display: none;
  }
  .checkout-stack__part {
    max-width: none;
    flex: 1 1 100%;
  }
}

/* Lecture 7 — test pyramid */
.test-pyramid__intro {
  text-align: center;
  max-width: 40rem;
  margin: 0 auto 16px;
}
.test-pyramid__badge {
  display: inline-block;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: #0d9488;
  background: linear-gradient(135deg, #ccfbf1, #e0f2fe);
  padding: 5px 12px;
  border-radius: 999px;
  margin-bottom: 10px;
}
.test-pyramid__title {
  margin: 0 0 8px;
  font-size: clamp(1.15rem, 2.4vw, 1.45rem);
  font-weight: 800;
  color: var(--heading);
}
.test-pyramid__subtitle {
  margin: 0;
  font-size: 14px;
  line-height: 1.5;
  color: var(--muted);
}
.test-pyramid__stack {
  max-width: 640px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.test-pyramid__row {
  display: flex;
  justify-content: center;
}
.test-pyramid__tier {
  width: calc(100% * var(--tier-scale, 0.75));
  padding: 12px 14px 14px;
  border-radius: 14px;
  border: 1px solid var(--border);
  text-align: center;
  background: var(--surface);
}
.test-pyramid__tier--unit {
  border-top: 4px solid #3b82f6;
  background: color-mix(in srgb, #eff6ff 40%, var(--surface));
}
.test-pyramid__tier--integration {
  border-top: 4px solid #8b5cf6;
  background: color-mix(in srgb, #f5f3ff 40%, var(--surface));
}
.test-pyramid__tier--system {
  border-top: 4px solid #10b981;
  background: color-mix(in srgb, #ecfdf5 40%, var(--surface));
}
.test-pyramid__tier--accept {
  border-top: 4px solid #f59e0b;
  background: color-mix(in srgb, #fffbeb 45%, var(--surface));
}
.test-pyramid__tier-label {
  display: block;
  font-size: 14px;
  font-weight: 800;
  color: var(--heading);
  margin-bottom: 6px;
}
.test-pyramid__tier-example {
  margin: 0 0 4px;
  font-size: 13px;
  line-height: 1.45;
  color: var(--text);
}
.test-pyramid__tier-note {
  margin: 0;
  font-size: 11.5px;
  font-weight: 700;
  color: var(--muted);
}
.test-pyramid__footnote {
  margin: 14px 4px 0;
  text-align: center;
  font-size: 13px;
  line-height: 1.5;
  color: var(--muted);
}

/* Lecture 7 — level × type matrix */
.coverage-matrix__intro {
  text-align: center;
  max-width: 40rem;
  margin: 0 auto 16px;
}
.coverage-matrix__badge {
  display: inline-block;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: #4f46e5;
  background: linear-gradient(135deg, #eef2ff, #e0e7ff);
  padding: 5px 12px;
  border-radius: 999px;
  margin-bottom: 10px;
}
.coverage-matrix__title {
  margin: 0 0 8px;
  font-size: clamp(1.1rem, 2.2vw, 1.35rem);
  font-weight: 800;
  color: var(--heading);
}
.coverage-matrix__subtitle {
  margin: 0;
  font-size: 14px;
  line-height: 1.5;
  color: var(--muted);
}
.coverage-matrix__board {
  max-width: 760px;
  margin: 0 auto;
  border-radius: 14px;
  border: 1px solid var(--border);
  overflow: hidden;
  background: var(--surface);
  font-size: 13px;
}
.coverage-matrix__colhead,
.coverage-matrix__row {
  display: grid;
  grid-template-columns: 118px repeat(4, 1fr);
}
.coverage-matrix__colhead {
  border-bottom: 1px solid var(--border);
  background: var(--surface-2);
}
.coverage-matrix__corner {
  border-right: 1px solid var(--border);
}
.coverage-matrix__colhead-cell {
  padding: 10px 8px;
  text-align: center;
  border-left: 1px solid var(--border);
}
.coverage-matrix__colhead-cell strong {
  display: block;
  font-size: 14px;
  font-weight: 800;
  color: var(--heading);
}
.coverage-matrix__colhead-cell small {
  display: block;
  margin-top: 2px;
  font-size: 12px;
  font-weight: 600;
  color: var(--muted);
}
.coverage-matrix__row {
  border-bottom: 1px solid var(--border);
}
.coverage-matrix__row:last-child {
  border-bottom: none;
}
.coverage-matrix__rowhead {
  padding: 10px 10px;
  border-right: 1px solid var(--border);
  background: color-mix(in srgb, var(--surface-2) 65%, var(--surface));
  border-left: 4px solid #6366f1;
}
.coverage-matrix__rowhead strong {
  display: block;
  font-size: 14px;
  font-weight: 800;
  color: var(--heading);
}
.coverage-matrix__rowhead strong {
  overflow-wrap: anywhere;
}
.coverage-matrix__rowhead small {
  display: block;
  margin-top: 2px;
  font-size: 11px;
  font-weight: 700;
  color: var(--muted);
}
.coverage-matrix__cell {
  padding: 10px 8px;
  line-height: 1.4;
  border-left: 1px solid var(--border);
  color: var(--text);
  font-size: 13.5px;
}
.coverage-matrix__cell--muted {
  color: var(--muted);
  font-style: italic;
}
.coverage-matrix__footnote {
  margin: 12px 4px 0;
  text-align: center;
  font-size: 13px;
  line-height: 1.45;
  color: var(--muted);
}
@media (max-width: 720px) {
  .coverage-matrix__board {
    overflow-x: auto;
  }
  .coverage-matrix__colhead,
  .coverage-matrix__row {
    min-width: 560px;
  }
}

/* Lecture 8 — vague requirement intro */
.req-vague-story__badge {
  margin: 0 0 14px;
  text-align: center;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: #b45309;
}
.req-vague-story__grid {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 12px;
  align-items: stretch;
  max-width: 680px;
  margin: 0 auto;
}
.req-vague-story__arrow {
  display: flex;
  align-items: center;
  font-size: 1.5rem;
  font-weight: 800;
  color: #93c5fd;
  padding-top: 2rem;
}
.req-vague-story__card {
  padding: 16px 16px 18px;
  border-radius: 14px;
  border: 1px solid var(--border);
  background: var(--surface);
  box-shadow: 0 12px 28px -20px rgba(37, 36, 80, 0.4);
}
.req-vague-story__card--vague {
  border-top: 4px solid #f43f5e;
}
.req-vague-story__card--clear {
  border-top: 4px solid #22c55e;
}
.req-vague-story__card-title {
  margin: 0 0 10px;
  font-size: 13px;
  font-weight: 800;
  color: var(--heading);
}
.req-vague-story__quote {
  margin: 0 0 12px;
  padding: 10px 12px;
  border-radius: 10px;
  font-size: 13px;
  font-weight: 700;
  line-height: 1.45;
  color: var(--heading);
  background: color-mix(in srgb, #fef2f2 50%, var(--surface-2));
  border: 1px dashed color-mix(in srgb, #f87171 40%, var(--border));
}
.req-vague-story__gaps {
  margin: 0;
  padding-left: 1.15rem;
  font-size: 12.5px;
  line-height: 1.5;
  color: var(--muted);
}
.req-vague-story__stack {
  margin: 0 0 10px;
  padding-left: 1.2rem;
  font-size: 12.5px;
  line-height: 1.55;
  color: var(--text);
}
.req-vague-story__note {
  margin: 0;
  font-size: 12px;
  line-height: 1.45;
  color: var(--muted);
}
@media (max-width: 640px) {
  .req-vague-story__grid {
    grid-template-columns: 1fr;
  }
  .req-vague-story__arrow {
    justify-content: center;
    padding: 0;
    transform: rotate(90deg);
  }
}

/* Lecture 8 — test case recipe */
.test-recipe__intro {
  text-align: center;
  max-width: 40rem;
  margin: 0 auto 16px;
}
.test-recipe__badge {
  display: inline-block;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: #4f46e5;
  background: linear-gradient(135deg, #eef2ff, #e0e7ff);
  padding: 5px 12px;
  border-radius: 999px;
  margin-bottom: 10px;
}
.test-recipe__title {
  margin: 0 0 8px;
  font-size: clamp(1.1rem, 2.2vw, 1.35rem);
  font-weight: 800;
  color: var(--heading);
}
.test-recipe__subtitle {
  margin: 0;
  font-size: 14px;
  line-height: 1.5;
  color: var(--muted);
}
.test-recipe__parts {
  list-style: none;
  margin: 0 auto;
  padding: 0;
  max-width: 520px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.test-recipe__part {
  position: relative;
  padding: 12px 14px 12px 44px;
  border-radius: 12px;
  border: 1px solid var(--border);
  background: var(--surface);
  counter-increment: recipe-part;
}
.test-recipe__parts {
  counter-reset: recipe-part;
}
.test-recipe__part::before {
  content: counter(recipe-part);
  position: absolute;
  left: 12px;
  top: 50%;
  transform: translateY(-50%);
  width: 24px;
  height: 24px;
  border-radius: 8px;
  display: grid;
  place-items: center;
  font-size: 11px;
  font-weight: 800;
  color: #fff;
  background: #6366f1;
}
.test-recipe__part--expect::before {
  background: #10b981;
}
.test-recipe__part--data::before {
  background: #8b5cf6;
}
.test-recipe__part-label {
  display: block;
  font-size: 11px;
  font-weight: 800;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--muted);
  margin-bottom: 4px;
}
.test-recipe__part-example {
  margin: 0;
  font-size: 13px;
  line-height: 1.45;
  color: var(--text);
  font-weight: 600;
}
.test-recipe__footnote {
  margin: 14px 4px 0;
  text-align: center;
  font-size: 13px;
  line-height: 1.5;
  color: var(--muted);
}

/* Lecture 8 — dual boundary number lines */
.boundary-dual__lead {
  margin: 0 auto 12px;
  max-width: 40rem;
  text-align: center;
  font-size: 13px;
  line-height: 1.5;
  color: var(--muted);
}
.boundary-dual__grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  max-width: 720px;
  margin: 0 auto;
}
.boundary-dual__panel .diagram {
  width: 100%;
  height: auto;
}
.boundary-dual__footnote {
  margin: 12px 4px 0;
  text-align: center;
  font-size: 12.5px;
  line-height: 1.45;
  color: var(--muted);
}
@media (max-width: 640px) {
  .boundary-dual__grid {
    grid-template-columns: 1fr;
  }
}

/* Lecture 9 — defect discovery intro */
.defect-discovery__badge {
  margin: 0 0 14px;
  text-align: center;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: #b45309;
}
.defect-discovery__grid {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 12px;
  align-items: stretch;
  max-width: 680px;
  margin: 0 auto;
}
.defect-discovery__arrow {
  display: flex;
  align-items: center;
  font-size: 1.5rem;
  font-weight: 800;
  color: #93c5fd;
  padding-top: 2rem;
}
.defect-discovery__card {
  padding: 16px 16px 18px;
  border-radius: 14px;
  border: 1px solid var(--border);
  background: var(--surface);
  box-shadow: 0 12px 28px -20px rgba(37, 36, 80, 0.4);
}
.defect-discovery__card--weak {
  border-top: 4px solid #f43f5e;
}
.defect-discovery__card--strong {
  border-top: 4px solid #22c55e;
}
.defect-discovery__card-title {
  margin: 0 0 10px;
  font-size: 13px;
  font-weight: 800;
  color: var(--heading);
}
.defect-discovery__chat,
.defect-discovery__summary {
  margin: 0 0 12px;
  padding: 10px 12px;
  border-radius: 10px;
  font-size: 12.5px;
  line-height: 1.45;
  font-weight: 600;
}
.defect-discovery__chat {
  background: color-mix(in srgb, #fef2f2 50%, var(--surface-2));
  border: 1px dashed color-mix(in srgb, #f87171 35%, var(--border));
  color: var(--text);
}
.defect-discovery__summary {
  background: color-mix(in srgb, #ecfdf5 50%, var(--surface-2));
  border: 1px solid color-mix(in srgb, #34d399 35%, var(--border));
  color: var(--heading);
}
.defect-discovery__pain,
.defect-discovery__wins {
  margin: 0;
  padding-left: 1.15rem;
  font-size: 12px;
  line-height: 1.5;
  color: var(--muted);
}
.defect-discovery__lesson {
  margin: 14px auto 0;
  max-width: 40rem;
  text-align: center;
  font-size: 13px;
  line-height: 1.5;
  color: var(--muted);
}
@media (max-width: 640px) {
  .defect-discovery__grid {
    grid-template-columns: 1fr;
  }
  .defect-discovery__arrow {
    justify-content: center;
    padding: 0;
    transform: rotate(90deg);
  }
}

/* Lecture 9 — defect lifecycle track */
.defect-lifecycle__intro {
  text-align: center;
  max-width: 40rem;
  margin: 0 auto 16px;
}
.defect-lifecycle__badge {
  display: inline-block;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: #dc2626;
  background: linear-gradient(135deg, #fee2e2, #ffedd5);
  padding: 5px 12px;
  border-radius: 999px;
  margin-bottom: 10px;
}
.defect-lifecycle__title {
  margin: 0 0 8px;
  font-size: clamp(1.1rem, 2.2vw, 1.35rem);
  font-weight: 800;
  color: var(--heading);
}
.defect-lifecycle__subtitle {
  margin: 0;
  font-size: 14px;
  line-height: 1.5;
  color: var(--muted);
}
.defect-lifecycle__track {
  display: flex;
  flex-wrap: wrap;
  align-items: stretch;
  justify-content: center;
  gap: 6px 4px;
  max-width: 760px;
  margin: 0 auto;
}
.defect-lifecycle__arrow {
  display: flex;
  align-items: center;
  font-size: 1.1rem;
  font-weight: 800;
  color: #93c5fd;
  padding-top: 1.25rem;
}
.defect-lifecycle__state {
  flex: 1 1 108px;
  max-width: 132px;
  padding: 10px 10px 12px;
  border-radius: 12px;
  border: 1px solid var(--border);
  background: var(--surface);
  text-align: center;
}
.defect-lifecycle__state--new { border-top: 3px solid #94a3b8; }
.defect-lifecycle__state--assigned { border-top: 3px solid #3b82f6; }
.defect-lifecycle__state--progress { border-top: 3px solid #8b5cf6; }
.defect-lifecycle__state--fixed { border-top: 3px solid #f59e0b; }
.defect-lifecycle__state--verified { border-top: 3px solid #22c55e; }
.defect-lifecycle__state-name {
  display: block;
  font-size: 12px;
  font-weight: 800;
  color: var(--heading);
  margin-bottom: 4px;
}
.defect-lifecycle__state-desc {
  margin: 0;
  font-size: 10.5px;
  line-height: 1.35;
  color: var(--muted);
}
.defect-lifecycle__branches {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 6px;
  margin-top: 14px;
  padding: 10px 12px;
  border-radius: 12px;
  background: var(--surface-2);
  border: 1px dashed var(--border);
  max-width: 760px;
  margin-left: auto;
  margin-right: auto;
}
.defect-lifecycle__branch {
  padding: 4px 10px;
  font-size: 10.5px;
  font-weight: 700;
  border-radius: 999px;
  background: var(--surface);
  border: 1px solid var(--border);
  color: var(--muted);
}
.defect-lifecycle__footnote {
  margin: 12px 4px 0;
  text-align: center;
  font-size: 12.5px;
  line-height: 1.45;
  color: var(--muted);
}

/* Lecture 10 — release readiness intro */
.release-readiness__badge {
  margin: 0 0 14px;
  text-align: center;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: #b45309;
}
.release-readiness__grid {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 12px;
  align-items: stretch;
  max-width: 680px;
  margin: 0 auto;
}
.release-readiness__arrow {
  display: flex;
  align-items: center;
  font-size: 1.5rem;
  font-weight: 800;
  color: #93c5fd;
  padding-top: 2rem;
}
.release-readiness__card {
  padding: 16px 16px 18px;
  border-radius: 14px;
  border: 1px solid var(--border);
  background: var(--surface);
  box-shadow: 0 12px 28px -20px rgba(37, 36, 80, 0.4);
}
.release-readiness__card--gap {
  border-top: 4px solid #f43f5e;
}
.release-readiness__card--clear {
  border-top: 4px solid #22c55e;
}
.release-readiness__card-title {
  margin: 0 0 4px;
  font-size: 13px;
  font-weight: 800;
  color: var(--heading);
}
.release-readiness__when {
  margin: 0 0 12px;
  font-size: 11px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--muted);
}
.release-readiness__list {
  margin: 0;
  padding-left: 1.15rem;
  font-size: 12px;
  line-height: 1.5;
  color: var(--muted);
}
.release-readiness__list--ok {
  color: var(--text);
}
.release-readiness__lesson {
  margin: 14px auto 0;
  max-width: 40rem;
  text-align: center;
  font-size: 13px;
  line-height: 1.5;
  color: var(--muted);
}
@media (max-width: 640px) {
  .release-readiness__grid {
    grid-template-columns: 1fr;
  }
  .release-readiness__arrow {
    justify-content: center;
    padding: 0;
    transform: rotate(90deg);
  }
}

/* Lecture 10 — execution metrics */
.execution-metrics__intro {
  text-align: center;
  max-width: 40rem;
  margin: 0 auto 16px;
}
.execution-metrics__badge {
  display: inline-block;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: #0d9488;
  background: linear-gradient(135deg, #ccfbf1, #e0f2fe);
  padding: 5px 12px;
  border-radius: 999px;
  margin-bottom: 10px;
}
.execution-metrics__title {
  margin: 0 0 8px;
  font-size: clamp(1.1rem, 2.2vw, 1.35rem);
  font-weight: 800;
  color: var(--heading);
}
.execution-metrics__subtitle {
  margin: 0;
  font-size: 14px;
  line-height: 1.5;
  color: var(--muted);
}
.execution-metrics__grid {
  display: grid;
  grid-template-columns: repeat(6, 1fr);
  gap: 8px;
  max-width: 720px;
  margin: 0 auto;
}
.execution-metrics__tile {
  padding: 12px 8px;
  border-radius: 12px;
  border: 1px solid var(--border);
  background: var(--surface);
  text-align: center;
}
.execution-metrics__tile--passed {
  border-top: 3px solid #22c55e;
  background: color-mix(in srgb, #ecfdf5 40%, var(--surface));
}
.execution-metrics__tile--failed {
  border-top: 3px solid #ef4444;
  background: color-mix(in srgb, #fef2f2 40%, var(--surface));
}
.execution-metrics__tile--blocked {
  border-top: 3px solid #f59e0b;
}
.execution-metrics__tile--skipped {
  border-top: 3px solid #94a3b8;
}
.execution-metrics__value {
  display: block;
  font-size: 1.35rem;
  font-weight: 800;
  color: var(--heading);
  line-height: 1.2;
}
.execution-metrics__label {
  display: block;
  margin-top: 4px;
  font-size: 10px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--muted);
}
.execution-metrics__pass {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: center;
  gap: 8px 12px;
  margin: 14px auto 0;
  padding: 12px 16px;
  max-width: 480px;
  border-radius: 12px;
  background: var(--surface-2);
  border: 1px solid var(--border);
}
.execution-metrics__pass-label {
  font-size: 12px;
  font-weight: 700;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}
.execution-metrics__pass-value {
  font-size: 1.5rem;
  font-weight: 800;
  color: #4f46e5;
}
.execution-metrics__pass-formula {
  font-size: 11.5px;
  color: var(--muted);
  flex: 1 1 100%;
  text-align: center;
}
.execution-metrics__callouts {
  margin: 12px auto 0;
  padding-left: 1.2rem;
  max-width: 520px;
  font-size: 12.5px;
  line-height: 1.5;
  color: var(--text);
}
.execution-metrics__footnote {
  margin: 12px 4px 0;
  text-align: center;
  font-size: 12.5px;
  line-height: 1.45;
  color: var(--muted);
}
@media (max-width: 640px) {
  .execution-metrics__grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

/* Lecture 11 — EP intro */
.ep-overload__badge {
  margin: 0 0 14px;
  text-align: center;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: #b45309;
}
.ep-overload__grid {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 12px;
  align-items: stretch;
  max-width: 680px;
  margin: 0 auto;
}
.ep-overload__arrow {
  display: flex;
  align-items: center;
  font-size: 1.5rem;
  font-weight: 800;
  color: #93c5fd;
  padding-top: 2rem;
}
.ep-overload__card {
  padding: 16px 16px 18px;
  border-radius: 14px;
  border: 1px solid var(--border);
  background: var(--surface);
  box-shadow: 0 12px 28px -20px rgba(37, 36, 80, 0.4);
}
.ep-overload__card--heavy {
  border-top: 4px solid #f43f5e;
}
.ep-overload__card--lean {
  border-top: 4px solid #22c55e;
}
.ep-overload__card-title {
  margin: 0 0 6px;
  font-size: 13px;
  font-weight: 800;
  color: var(--heading);
}
.ep-overload__stat {
  margin: 0 0 10px;
  font-size: 11.5px;
  font-weight: 700;
  color: var(--muted);
}
.ep-overload__list {
  margin: 0;
  padding-left: 1.15rem;
  font-size: 12px;
  line-height: 1.5;
  color: var(--muted);
}
.ep-overload__list--ok {
  color: var(--text);
}
.ep-overload__lesson {
  margin: 14px auto 0;
  max-width: 40rem;
  text-align: center;
  font-size: 13px;
  line-height: 1.5;
  color: var(--muted);
}
@media (max-width: 640px) {
  .ep-overload__grid {
    grid-template-columns: 1fr;
  }
  .ep-overload__arrow {
    justify-content: center;
    padding: 0;
    transform: rotate(90deg);
  }
}

/* Lecture 11 — cart partitions */
.cart-partitions__intro {
  text-align: center;
  max-width: 40rem;
  margin: 0 auto 16px;
}
.cart-partitions__badge {
  display: inline-block;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: #4f46e5;
  background: linear-gradient(135deg, #eef2ff, #e0e7ff);
  padding: 5px 12px;
  border-radius: 999px;
  margin-bottom: 10px;
}
.cart-partitions__title {
  margin: 0 0 8px;
  font-size: clamp(1.1rem, 2.2vw, 1.35rem);
  font-weight: 800;
  color: var(--heading);
}
.cart-partitions__subtitle {
  margin: 0;
  font-size: 14px;
  line-height: 1.5;
  color: var(--muted);
}
.cart-partitions__valid {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  align-items: center;
  gap: 10px 16px;
  margin: 0 auto 14px;
  padding: 14px 16px;
  max-width: 560px;
  border-radius: 14px;
  border: 1px solid color-mix(in srgb, #22c55e 35%, var(--border));
  background: color-mix(in srgb, #ecfdf5 45%, var(--surface));
}
.cart-partitions__valid-label {
  font-size: 13px;
  font-weight: 800;
  color: #047857;
}
.cart-partitions__valid-rep {
  font-size: 13px;
  color: var(--text);
}
.cart-partitions__invalids {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
  gap: 8px;
  max-width: 720px;
  margin: 0 auto;
}
.cart-partitions__chip {
  padding: 10px 12px;
  border-radius: 12px;
  border: 1px solid var(--border);
  background: color-mix(in srgb, #fef2f2 35%, var(--surface));
  border-top: 3px solid #f87171;
  text-align: center;
}
.cart-partitions__chip-label {
  display: block;
  font-size: 10px;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--muted);
  margin-bottom: 4px;
}
.cart-partitions__chip-value {
  display: block;
  font-size: 14px;
  font-weight: 800;
  color: var(--heading);
}
.cart-partitions__chip-tc {
  display: block;
  margin-top: 4px;
  font-size: 10.5px;
  font-weight: 700;
  color: #4f46e5;
}
.cart-partitions__footnote {
  margin: 14px 4px 0;
  text-align: center;
  font-size: 12.5px;
  line-height: 1.45;
  color: var(--muted);
}

/* Lecture 12 — BVA intro */
.bva-gate__badge {
  margin: 0 0 14px;
  text-align: center;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: #b45309;
}
.bva-gate__grid {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 12px;
  align-items: stretch;
  max-width: 680px;
  margin: 0 auto;
}
.bva-gate__arrow {
  display: flex;
  align-items: center;
  font-size: 1.5rem;
  font-weight: 800;
  color: #93c5fd;
  padding-top: 2rem;
}
.bva-gate__card {
  padding: 16px 16px 18px;
  border-radius: 14px;
  border: 1px solid var(--border);
  background: var(--surface);
  box-shadow: 0 12px 28px -20px rgba(37, 36, 80, 0.4);
}
.bva-gate__card--bug {
  border-top: 4px solid #f43f5e;
}
.bva-gate__card--fix {
  border-top: 4px solid #22c55e;
}
.bva-gate__card-title {
  margin: 0 0 8px;
  font-size: 13px;
  font-weight: 800;
  color: var(--heading);
}
.bva-gate__card-title code {
  font-size: 12px;
  padding: 2px 6px;
  border-radius: 6px;
  background: var(--surface-2);
}
.bva-gate__req {
  margin: 0 0 10px;
  font-size: 12px;
  line-height: 1.45;
  color: var(--muted);
}
.bva-gate__list {
  margin: 0;
  padding-left: 1.15rem;
  font-size: 12px;
  line-height: 1.5;
  color: var(--muted);
}
.bva-gate__list--ok {
  color: var(--text);
}
.bva-gate__lesson {
  margin: 14px auto 0;
  max-width: 40rem;
  text-align: center;
  font-size: 13px;
  line-height: 1.5;
  color: var(--muted);
}
@media (max-width: 640px) {
  .bva-gate__grid {
    grid-template-columns: 1fr;
  }
  .bva-gate__arrow {
    justify-content: center;
    padding: 0;
    transform: rotate(90deg);
  }
}

/* Lecture 12 — three-value boundary bands */
.boundary-triple__intro {
  text-align: center;
  max-width: 40rem;
  margin: 0 auto 16px;
}
.boundary-triple__badge {
  display: inline-block;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: #7c3aed;
  background: linear-gradient(135deg, #ede9fe, #e0e7ff);
  padding: 5px 12px;
  border-radius: 999px;
  margin-bottom: 10px;
}
.boundary-triple__title {
  margin: 0 0 8px;
  font-size: clamp(1.1rem, 2.2vw, 1.35rem);
  font-weight: 800;
  color: var(--heading);
}
.boundary-triple__subtitle {
  margin: 0;
  font-size: 14px;
  line-height: 1.5;
  color: var(--muted);
}
.boundary-triple__bands {
  display: grid;
  gap: 14px;
  max-width: 640px;
  margin: 0 auto;
}
.boundary-triple__band-title {
  margin: 0 0 10px;
  font-size: 12px;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--muted);
  text-align: center;
}
.boundary-triple__values {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 8px;
}
.boundary-triple__cell {
  padding: 12px 10px;
  border-radius: 12px;
  border: 1px solid var(--border);
  text-align: center;
  background: var(--surface);
}
.boundary-triple__cell--ok {
  border-top: 3px solid #22c55e;
  background: color-mix(in srgb, #ecfdf5 40%, var(--surface));
}
.boundary-triple__cell--bad {
  border-top: 3px solid #ef4444;
  background: color-mix(in srgb, #fef2f2 40%, var(--surface));
}
.boundary-triple__len {
  display: block;
  font-size: 1.35rem;
  font-weight: 800;
  color: var(--heading);
}
.boundary-triple__tc {
  display: block;
  margin-top: 4px;
  font-size: 10.5px;
  font-weight: 800;
  color: #4f46e5;
}
.boundary-triple__note {
  display: block;
  margin-top: 4px;
  font-size: 10.5px;
  color: var(--muted);
  line-height: 1.35;
}
.boundary-triple__footnote {
  margin: 14px 4px 0;
  text-align: center;
  font-size: 12.5px;
  line-height: 1.45;
  color: var(--muted);
}
@media (max-width: 520px) {
  .boundary-triple__values {
    grid-template-columns: 1fr;
  }
}

/* Lecture 13 — pricing combo intro */
.pricing-combo__badge {
  margin: 0 0 10px;
  text-align: center;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: #b45309;
}
.pricing-combo__lead {
  margin: 0 auto 14px;
  max-width: 40rem;
  text-align: center;
  font-size: 13.5px;
  line-height: 1.5;
  color: var(--text);
}
.pricing-combo__grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px;
  max-width: 560px;
  margin: 0 auto;
}
.pricing-combo__cell {
  padding: 12px 14px 14px;
  border-radius: 12px;
  border: 1px solid var(--border);
  background: var(--surface);
  box-shadow: 0 10px 24px -18px rgba(37, 36, 80, 0.45);
  font-size: 12px;
  line-height: 1.45;
  color: var(--muted);
}
.pricing-combo__cell strong {
  display: block;
  margin-bottom: 4px;
  font-size: 12.5px;
  color: var(--heading);
}
.pricing-combo__cell p {
  margin: 0;
}
.pricing-combo__rule {
  display: inline-block;
  margin-bottom: 6px;
  padding: 2px 8px;
  border-radius: 999px;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.04em;
  background: color-mix(in srgb, #6366f1 12%, var(--surface-2));
  color: #4f46e5;
}
.pricing-combo__cell--r1 { border-top: 3px solid #22c55e; }
.pricing-combo__cell--r2 { border-top: 3px solid #3b82f6; }
.pricing-combo__cell--r3 { border-top: 3px solid #8b5cf6; }
.pricing-combo__cell--r4 { border-top: 3px solid #f59e0b; }
.pricing-combo__lesson {
  margin: 14px auto 0;
  max-width: 40rem;
  text-align: center;
  font-size: 13px;
  line-height: 1.5;
  color: var(--muted);
}
@media (max-width: 480px) {
  .pricing-combo__grid {
    grid-template-columns: 1fr;
  }
}

/* Lecture 13 — decision table artifact */
.decision-table-wrap__intro {
  margin-bottom: 12px;
  text-align: center;
}
.decision-table-wrap__badge {
  display: inline-block;
  margin-bottom: 6px;
  padding: 3px 10px;
  border-radius: 999px;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  background: color-mix(in srgb, #6366f1 14%, var(--surface-2));
  color: #4f46e5;
}
.decision-table-wrap__title {
  margin: 0 0 4px;
  font-size: 1.15rem;
  font-weight: 800;
  color: var(--heading);
}
.decision-table-wrap__subtitle {
  margin: 0;
  font-size: 14px;
  line-height: 1.45;
  color: var(--muted);
}
.decision-table-wrap__scroll {
  overflow-x: auto;
  margin: 0 -4px;
  padding: 4px;
  -webkit-overflow-scrolling: touch;
}
.decision-table {
  width: 100%;
  min-width: 520px;
  border-collapse: separate;
  border-spacing: 0;
  font-size: 13.5px;
  line-height: 1.4;
  border: 1px solid var(--border);
  border-radius: 12px;
  overflow: hidden;
  background: var(--surface);
}
.decision-table thead th {
  padding: 10px 8px;
  background: color-mix(in srgb, #6366f1 8%, var(--surface-2));
  border-bottom: 1px solid var(--border);
  font-weight: 800;
  color: var(--heading);
  text-align: center;
  vertical-align: bottom;
}
.decision-table thead th:first-child {
  text-align: left;
  min-width: 11rem;
}
.decision-table__colsub {
  display: block;
  margin-top: 3px;
  font-size: 10px;
  font-weight: 600;
  color: var(--muted);
}
.decision-table__section th {
  padding: 6px 10px;
  text-align: left;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--muted);
  background: var(--surface-2);
  border-bottom: 1px solid var(--border);
}
.decision-table tbody th {
  padding: 8px 10px;
  text-align: left;
  font-weight: 600;
  color: var(--text);
  background: var(--surface);
  border-bottom: 1px solid color-mix(in srgb, var(--border) 70%, transparent);
}
.decision-table__rowid {
  display: inline-block;
  min-width: 1.75rem;
  margin-right: 6px;
  font-size: 10px;
  font-weight: 800;
  color: #6366f1;
}
.decision-table__row--cond th {
  background: color-mix(in srgb, #3b82f6 6%, var(--surface));
}
.decision-table__row--act th {
  background: color-mix(in srgb, #22c55e 5%, var(--surface));
}
.decision-table td {
  padding: 8px 8px;
  text-align: center;
  font-weight: 700;
  border-bottom: 1px solid color-mix(in srgb, var(--border) 70%, transparent);
  border-left: 1px solid color-mix(in srgb, var(--border) 50%, transparent);
}
.decision-table__cell--yes {
  background: color-mix(in srgb, var(--ok-bg) 55%, var(--surface));
  color: var(--ok);
}
.decision-table__cell--no {
  background: color-mix(in srgb, var(--surface-2) 80%, var(--surface));
  color: var(--muted);
  font-weight: 600;
}
.decision-table__cell--hi {
  box-shadow: inset 0 0 0 2px color-mix(in srgb, #22c55e 45%, transparent);
}
.decision-table-wrap__footnote {
  margin: 12px 4px 0;
  text-align: center;
  font-size: 14px;
  line-height: 1.45;
  color: var(--muted);
}
.decision-table__cell--transition {
  background: color-mix(in srgb, #6366f1 10%, var(--surface));
  color: var(--heading);
  font-weight: 800;
  font-size: 11.5px;
}
.state-transition-table__row--created th { border-left: 3px solid #94a3b8; }
.state-transition-table__row--paid th { border-left: 3px solid #3b82f6; }
.state-transition-table__row--shipped th { border-left: 3px solid #8b5cf6; }
.state-transition-table__row--delivered th { border-left: 3px solid #22c55e; }
.state-transition-table__row--cancelled th { border-left: 3px solid #f43f5e; }

/* Lecture 14 — lifecycle intro */
.order-lifecycle-gap__badge {
  margin: 0 0 14px;
  text-align: center;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: #b45309;
}
.order-lifecycle-gap__grid {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 12px;
  align-items: stretch;
  max-width: 680px;
  margin: 0 auto;
}
.order-lifecycle-gap__arrow {
  display: flex;
  align-items: center;
  font-size: 1.5rem;
  font-weight: 800;
  color: #93c5fd;
  padding-top: 2rem;
}
.order-lifecycle-gap__card {
  padding: 16px 16px 18px;
  border-radius: 14px;
  border: 1px solid var(--border);
  background: var(--surface);
  box-shadow: 0 12px 28px -20px rgba(37, 36, 80, 0.4);
}
.order-lifecycle-gap__card--screens { border-top: 4px solid #22c55e; }
.order-lifecycle-gap__card--bug { border-top: 4px solid #f43f5e; }
.order-lifecycle-gap__card-title {
  margin: 0 0 10px;
  font-size: 13px;
  font-weight: 800;
  color: var(--heading);
}
.order-lifecycle-gap__list {
  margin: 0;
  padding-left: 1.15rem;
  font-size: 12px;
  line-height: 1.5;
  color: var(--text);
}
.order-lifecycle-gap__list--bad { color: var(--muted); }
.order-lifecycle-gap__note {
  margin: 12px 0 0;
  font-size: 11.5px;
  line-height: 1.45;
  color: var(--muted);
}
.order-lifecycle-gap__status {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin: 0 0 8px;
  padding: 8px 10px;
  border-radius: 10px;
  background: var(--surface-2);
  font-size: 12px;
}
.order-lifecycle-gap__status strong {
  color: #8b5cf6;
}
.order-lifecycle-gap__bad {
  margin: 0 0 10px;
  font-size: 12px;
  line-height: 1.45;
  color: #b91c1c;
}
.order-lifecycle-gap__lesson {
  margin: 14px auto 0;
  max-width: 40rem;
  text-align: center;
  font-size: 13px;
  line-height: 1.5;
  color: var(--muted);
}
@media (max-width: 640px) {
  .order-lifecycle-gap__grid {
    grid-template-columns: 1fr;
  }
  .order-lifecycle-gap__arrow {
    justify-content: center;
    padding: 0;
    transform: rotate(90deg);
  }
}

/* Lecture 14 — state model diagram */
.state-model__intro {
  margin-bottom: 14px;
  text-align: center;
}
.state-model__badge {
  display: inline-block;
  margin-bottom: 6px;
  padding: 3px 10px;
  border-radius: 999px;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  background: color-mix(in srgb, #3b82f6 14%, var(--surface-2));
  color: #2563eb;
}
.state-model__title {
  margin: 0 0 4px;
  font-size: 1.15rem;
  font-weight: 800;
  color: var(--heading);
}
.state-model__subtitle {
  margin: 0;
  font-size: 12.5px;
  line-height: 1.45;
  color: var(--muted);
}
.state-model__path {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: center;
  gap: 6px 4px;
  max-width: 720px;
  margin: 0 auto 16px;
}
.state-model__node {
  padding: 10px 12px 11px;
  border-radius: 12px;
  border: 1px solid var(--border);
  background: var(--surface);
  box-shadow: 0 8px 20px -16px rgba(37, 36, 80, 0.45);
  text-align: center;
  min-width: 5.5rem;
}
.state-model__node-name {
  display: block;
  font-size: 12px;
  font-weight: 800;
  color: var(--heading);
}
.state-model__node--created { border-top: 3px solid #94a3b8; }
.state-model__node--paid { border-top: 3px solid #3b82f6; }
.state-model__node--shipped { border-top: 3px solid #8b5cf6; }
.state-model__node--delivered { border-top: 3px solid #22c55e; }
.state-model__node--cancelled { border-top: 3px solid #f43f5e; }
.state-model__edge {
  display: inline-flex;
  flex-direction: column;
  align-items: center;
  gap: 2px;
  padding: 0 2px;
  color: var(--muted);
}
.state-model__event {
  font-size: 9.5px;
  font-weight: 800;
  letter-spacing: 0.03em;
  text-transform: uppercase;
  color: #6366f1;
  white-space: nowrap;
}
.state-model__arrow {
  font-size: 1.1rem;
  font-weight: 800;
  line-height: 1;
}
.state-model__branch {
  max-width: 28rem;
  margin: 0 auto;
  padding: 14px 16px;
  border-radius: 14px;
  border: 1px dashed color-mix(in srgb, #f43f5e 35%, var(--border));
  background: color-mix(in srgb, #fef2f2 40%, var(--surface));
  text-align: center;
}
.state-model__branch-label {
  margin: 0 0 8px;
  font-size: 12px;
  line-height: 1.45;
  color: var(--text);
}
.state-model__branch-arrow {
  display: block;
  margin: 4px 0 10px;
  font-size: 1.25rem;
  color: #f43f5e;
}
.state-model__terminal {
  display: block;
  margin-top: 4px;
  font-size: 9px;
  font-weight: 800;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--muted);
}
.state-model__branch-note {
  margin: 12px 0 0;
  font-size: 11.5px;
  line-height: 1.45;
  color: var(--muted);
}
.state-model__footnote {
  margin: 14px 4px 0;
  text-align: center;
  font-size: 12.5px;
  line-height: 1.45;
  color: var(--muted);
}

/* Lecture 15 — combo explosion intro */
.pairwise-blast__badge {
  margin: 0 0 14px;
  text-align: center;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: #b45309;
}
.pairwise-blast__grid {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 12px;
  align-items: stretch;
  max-width: 680px;
  margin: 0 auto;
}
.pairwise-blast__arrow {
  display: flex;
  align-items: center;
  font-size: 1.5rem;
  font-weight: 800;
  color: #93c5fd;
  padding-top: 2rem;
}
.pairwise-blast__card {
  padding: 16px 16px 18px;
  border-radius: 14px;
  border: 1px solid var(--border);
  background: var(--surface);
  box-shadow: 0 12px 28px -20px rgba(37, 36, 80, 0.4);
  text-align: center;
}
.pairwise-blast__card--small { border-top: 4px solid #22c55e; }
.pairwise-blast__card--large { border-top: 4px solid #f59e0b; }
.pairwise-blast__card-title {
  margin: 0 0 8px;
  font-size: 13px;
  font-weight: 800;
  color: var(--heading);
}
.pairwise-blast__formula {
  margin: 0 0 6px;
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.04em;
  color: var(--muted);
}
.pairwise-blast__count {
  margin: 0 0 8px;
  font-size: 12.5px;
  color: var(--text);
}
.pairwise-blast__count strong {
  font-size: 1.75rem;
  font-weight: 800;
  color: var(--heading);
}
.pairwise-blast__note {
  margin: 0;
  font-size: 11.5px;
  line-height: 1.45;
  color: var(--muted);
}
.pairwise-blast__lesson {
  margin: 14px auto 0;
  max-width: 40rem;
  text-align: center;
  font-size: 13px;
  line-height: 1.5;
  color: var(--muted);
}
@media (max-width: 640px) {
  .pairwise-blast__grid {
    grid-template-columns: 1fr;
  }
  .pairwise-blast__arrow {
    justify-content: center;
    padding: 0;
    transform: rotate(90deg);
  }
}

/* Lecture 15 — pairwise test set table */
.pairwise-set__stats {
  margin: 0 auto 12px;
  max-width: 36rem;
  text-align: center;
  font-size: 12.5px;
  line-height: 1.45;
  color: var(--muted);
}
.pairwise-set__tc {
  font-size: 11px;
  font-weight: 800;
  color: #6366f1;
  letter-spacing: 0.03em;
}
.pairwise-set-table tbody th {
  vertical-align: middle;
}

/* Lecture 16 — use case intro */
.use-case-gap__badge {
  margin: 0 0 14px;
  text-align: center;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: #b45309;
}
.use-case-gap__grid {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 12px;
  align-items: stretch;
  max-width: 680px;
  margin: 0 auto;
}
.use-case-gap__arrow {
  display: flex;
  align-items: center;
  font-size: 1.5rem;
  font-weight: 800;
  color: #93c5fd;
  padding-top: 2rem;
}
.use-case-gap__card {
  padding: 16px 16px 18px;
  border-radius: 14px;
  border: 1px solid var(--border);
  background: var(--surface);
  box-shadow: 0 12px 28px -20px rgba(37, 36, 80, 0.4);
}
.use-case-gap__card--screens { border-top: 4px solid #22c55e; }
.use-case-gap__card--break { border-top: 4px solid #f43f5e; }
.use-case-gap__card-title {
  margin: 0 0 10px;
  font-size: 13px;
  font-weight: 800;
  color: var(--heading);
}
.use-case-gap__list {
  margin: 0;
  padding-left: 1.15rem;
  font-size: 12px;
  line-height: 1.5;
  color: var(--text);
}
.use-case-gap__list--bad { color: var(--muted); }
.use-case-gap__note,
.use-case-gap__cause {
  margin: 12px 0 0;
  font-size: 11.5px;
  line-height: 1.45;
  color: var(--muted);
}
.use-case-gap__confirm {
  margin: 0 0 10px;
  padding: 10px 12px;
  border-radius: 10px;
  text-align: center;
  font-size: 12px;
  font-weight: 700;
  color: #15803d;
  background: color-mix(in srgb, #dcfce7 50%, var(--surface));
  border: 1px solid color-mix(in srgb, #22c55e 35%, var(--border));
}
.use-case-gap__lesson {
  margin: 14px auto 0;
  max-width: 40rem;
  text-align: center;
  font-size: 13px;
  line-height: 1.5;
  color: var(--muted);
}
@media (max-width: 640px) {
  .use-case-gap__grid {
    grid-template-columns: 1fr;
  }
  .use-case-gap__arrow {
    justify-content: center;
    padding: 0;
    transform: rotate(90deg);
  }
}

/* Lecture 16 — UC path diagram */
.use-case-flow__intro {
  margin-bottom: 12px;
  text-align: center;
}
.use-case-flow__badge {
  display: inline-block;
  margin-bottom: 6px;
  padding: 3px 10px;
  border-radius: 999px;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  background: color-mix(in srgb, #0ea5e9 14%, var(--surface-2));
  color: #0284c7;
}
.use-case-flow__title {
  margin: 0 0 4px;
  font-size: 1.15rem;
  font-weight: 800;
  color: var(--heading);
}
.use-case-flow__subtitle {
  margin: 0;
  font-size: 12.5px;
  line-height: 1.45;
  color: var(--muted);
}
.use-case-flow__section-label {
  margin: 0 0 8px;
  text-align: center;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--muted);
}
.use-case-flow__track {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: center;
  gap: 4px 6px;
  max-width: 640px;
  margin: 0 auto 14px;
}
.use-case-flow__step {
  padding: 8px 11px;
  border-radius: 10px;
  border: 1px solid var(--border);
  background: color-mix(in srgb, #22c55e 8%, var(--surface));
  font-size: 11.5px;
  font-weight: 700;
  color: var(--heading);
  box-shadow: 0 6px 16px -14px rgba(37, 36, 80, 0.5);
}
.use-case-flow__arrow {
  font-size: 1.1rem;
  font-weight: 800;
  color: var(--muted);
}
.use-case-flow__branch {
  max-width: 36rem;
  margin: 0 auto 10px;
  padding: 12px 14px;
  border-radius: 12px;
  border: 1px solid var(--border);
  background: var(--surface-2);
}
.use-case-flow__branch--alt {
  border-left: 3px solid #8b5cf6;
}
.use-case-flow__branch--ex {
  border-left: 3px solid #f59e0b;
}
.use-case-flow__branch-title {
  margin: 0 0 8px;
  font-size: 11px;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--heading);
}
.use-case-flow__branch-title span {
  font-weight: 600;
  text-transform: none;
  letter-spacing: 0;
  color: var(--muted);
}
.use-case-flow__branch-list {
  margin: 0;
  padding-left: 1.1rem;
  font-size: 11.5px;
  line-height: 1.5;
  color: var(--text);
}
.use-case-flow__branch-list strong {
  color: #6366f1;
}
.use-case-flow__footnote {
  margin: 12px 4px 0;
  text-align: center;
  font-size: 12.5px;
  line-height: 1.45;
  color: var(--muted);
}
.use-case-paths-table__row--main th { border-left: 3px solid #22c55e; }
.use-case-paths-table__row--alt th { border-left: 3px solid #8b5cf6; }
.use-case-paths-table__row--ex th { border-left: 3px solid #f59e0b; }

/* Lecture 17 — exploratory intro */
.explore-gap__badge {
  margin: 0 0 14px;
  text-align: center;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: #b45309;
}
.explore-gap__grid {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 12px;
  align-items: stretch;
  max-width: 680px;
  margin: 0 auto;
}
.explore-gap__arrow {
  display: flex;
  align-items: center;
  font-size: 1.5rem;
  font-weight: 800;
  color: #93c5fd;
  padding-top: 2rem;
}
.explore-gap__card {
  padding: 16px 16px 18px;
  border-radius: 14px;
  border: 1px solid var(--border);
  background: var(--surface);
  box-shadow: 0 12px 28px -20px rgba(37, 36, 80, 0.4);
}
.explore-gap__card--script { border-top: 4px solid #22c55e; }
.explore-gap__card--find { border-top: 4px solid #f59e0b; }
.explore-gap__card-title {
  margin: 0 0 10px;
  font-size: 13px;
  font-weight: 800;
  color: var(--heading);
}
.explore-gap__list {
  margin: 0;
  padding-left: 1.15rem;
  font-size: 12px;
  line-height: 1.5;
  color: var(--text);
}
.explore-gap__list--bad { color: var(--muted); }
.explore-gap__note,
.explore-gap__bug {
  margin: 12px 0 0;
  font-size: 11.5px;
  line-height: 1.45;
  color: var(--muted);
}
.explore-gap__sequence {
  margin: 0 0 10px;
  padding: 8px 10px;
  border-radius: 10px;
  font-size: 11px;
  line-height: 1.45;
  background: color-mix(in srgb, #fef3c7 55%, var(--surface));
  border: 1px solid color-mix(in srgb, #f59e0b 30%, var(--border));
  color: var(--text);
}
.explore-gap__lesson {
  margin: 14px auto 0;
  max-width: 40rem;
  text-align: center;
  font-size: 13px;
  line-height: 1.5;
  color: var(--muted);
}
@media (max-width: 640px) {
  .explore-gap__grid {
    grid-template-columns: 1fr;
  }
  .explore-gap__arrow {
    justify-content: center;
    padding: 0;
    transform: rotate(90deg);
  }
}

/* Lecture 17 — charter card */
.explore-charter__intro {
  margin-bottom: 12px;
  text-align: center;
}
.explore-charter__badge {
  display: inline-block;
  margin-bottom: 6px;
  padding: 3px 10px;
  border-radius: 999px;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  background: color-mix(in srgb, #14b8a6 14%, var(--surface-2));
  color: #0d9488;
}
.explore-charter__title {
  margin: 0 0 4px;
  font-size: 1.15rem;
  font-weight: 800;
  color: var(--heading);
}
.explore-charter__subtitle {
  margin: 0;
  font-size: 12.5px;
  line-height: 1.45;
  color: var(--muted);
}
.explore-charter__card {
  max-width: 36rem;
  margin: 0 auto;
  padding: 14px 16px 16px;
  border-radius: 14px;
  border: 1px solid var(--border);
  background: var(--surface);
  box-shadow: 0 10px 24px -18px rgba(37, 36, 80, 0.45);
}
.explore-charter__label {
  margin: 10px 0 4px;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: #0d9488;
}
.explore-charter__label:first-of-type {
  margin-top: 0;
}
.explore-charter__value {
  margin: 0 0 4px;
  font-size: 12.5px;
  line-height: 1.5;
  color: var(--text);
}
.explore-charter__footnote {
  margin: 12px 4px 0;
  text-align: center;
  font-size: 12.5px;
  line-height: 1.45;
  color: var(--muted);
}

/* Lecture 17 — session log */
.session-log-table__time {
  font-size: 11px;
  font-weight: 800;
  color: #6366f1;
  white-space: nowrap;
}
.session-log-table__row--find th {
  border-left: 3px solid #f59e0b;
}
.session-log-table__row--ok th {
  border-left: 3px solid #94a3b8;
}
.session-log-table td {
  font-size: 11.5px;
  line-height: 1.4;
  text-align: left;
  font-weight: 600;
}

/* Lecture 18 — risk intro */
.risk-crunch__badge {
  margin: 0 0 14px;
  text-align: center;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: #b45309;
}
.risk-crunch__grid {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 12px;
  align-items: stretch;
  max-width: 680px;
  margin: 0 auto;
}
.risk-crunch__arrow {
  display: flex;
  align-items: center;
  font-size: 1.5rem;
  font-weight: 800;
  color: #93c5fd;
  padding-top: 2rem;
}
.risk-crunch__card {
  padding: 16px 16px 18px;
  border-radius: 14px;
  border: 1px solid var(--border);
  background: var(--surface);
  box-shadow: 0 12px 28px -20px rgba(37, 36, 80, 0.4);
}
.risk-crunch__card--limit { border-top: 4px solid #f59e0b; }
.risk-crunch__card--split { border-top: 4px solid #6366f1; }
.risk-crunch__card-title {
  margin: 0 0 10px;
  font-size: 13px;
  font-weight: 800;
  color: var(--heading);
}
.risk-crunch__stat {
  margin: 0 0 6px;
  font-size: 12px;
  color: var(--text);
}
.risk-crunch__stat strong {
  font-size: 1.5rem;
  font-weight: 800;
  color: var(--heading);
}
.risk-crunch__stat--dim {
  color: var(--muted);
}
.risk-crunch__list {
  margin: 0;
  padding: 0;
  list-style: none;
}
.risk-crunch__item {
  margin: 0 0 8px;
  padding: 8px 10px;
  border-radius: 10px;
  font-size: 12px;
  line-height: 1.45;
}
.risk-crunch__item--high {
  background: color-mix(in srgb, #fef2f2 55%, var(--surface));
  border: 1px solid color-mix(in srgb, #f43f5e 25%, var(--border));
}
.risk-crunch__item--low {
  background: var(--surface-2);
  border: 1px solid var(--border);
}
.risk-crunch__note {
  margin: 12px 0 0;
  font-size: 11.5px;
  line-height: 1.45;
  color: var(--muted);
}
.risk-crunch__lesson {
  margin: 14px auto 0;
  max-width: 40rem;
  text-align: center;
  font-size: 13px;
  line-height: 1.5;
  color: var(--muted);
}
@media (max-width: 640px) {
  .risk-crunch__grid {
    grid-template-columns: 1fr;
  }
  .risk-crunch__arrow {
    justify-content: center;
    padding: 0;
    transform: rotate(90deg);
  }
}

/* Lecture 18 — risk heatmap */
.risk-heatmap__intro {
  margin-bottom: 12px;
  text-align: center;
}
.risk-heatmap__badge {
  display: inline-block;
  margin-bottom: 6px;
  padding: 3px 10px;
  border-radius: 999px;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  background: color-mix(in srgb, #f43f5e 12%, var(--surface-2));
  color: #dc2626;
}
.risk-heatmap__title {
  margin: 0 0 4px;
  font-size: 1.15rem;
  font-weight: 800;
  color: var(--heading);
}
.risk-heatmap__subtitle {
  margin: 0;
  font-size: 12.5px;
  line-height: 1.45;
  color: var(--muted);
}
.risk-heatmap__scroll {
  overflow-x: auto;
  margin: 0 -4px;
  padding: 4px;
}
.risk-heatmap__table {
  width: 100%;
  min-width: 420px;
  border-collapse: separate;
  border-spacing: 0;
  border: 1px solid var(--border);
  border-radius: 12px;
  overflow: hidden;
  font-size: 12px;
}
.risk-heatmap__table th {
  padding: 10px 8px;
  background: var(--surface-2);
  border-bottom: 1px solid var(--border);
  font-weight: 800;
  color: var(--heading);
  text-align: center;
}
.risk-heatmap__table thead th:first-child {
  text-align: left;
  font-size: 10px;
}
.risk-heatmap__table tbody th {
  text-align: left;
  font-size: 11px;
  background: var(--surface);
  border-bottom: 1px solid color-mix(in srgb, var(--border) 70%, transparent);
}
.risk-heatmap__cell {
  padding: 12px 8px;
  text-align: center;
  border-bottom: 1px solid color-mix(in srgb, var(--border) 70%, transparent);
  border-left: 1px solid color-mix(in srgb, var(--border) 50%, transparent);
}
.risk-heatmap__cell--low {
  background: color-mix(in srgb, var(--ok-bg) 50%, var(--surface));
}
.risk-heatmap__cell--mid {
  background: color-mix(in srgb, #fef3c7 45%, var(--surface));
}
.risk-heatmap__cell--high {
  background: color-mix(in srgb, #fed7aa 50%, var(--surface));
}
.risk-heatmap__cell--critical {
  background: color-mix(in srgb, var(--bad-bg) 55%, var(--surface));
}
.risk-heatmap__score {
  display: block;
  font-size: 1.25rem;
  font-weight: 800;
  color: var(--heading);
}
.risk-heatmap__depth {
  display: block;
  margin-top: 4px;
  font-size: 10px;
  font-weight: 700;
  line-height: 1.35;
  color: var(--muted);
}
.risk-heatmap__footnote {
  margin: 12px 4px 0;
  text-align: center;
  font-size: 12.5px;
  line-height: 1.45;
  color: var(--muted);
}

/* Lecture 18 — risk register */
.risk-register-table {
  min-width: 640px;
  font-size: 11px;
}
.risk-register-table__text {
  text-align: left;
  font-weight: 600;
  font-size: 11px;
  line-height: 1.35;
}
.risk-register-table__score {
  font-weight: 800;
  font-size: 13px;
}
.risk-register-table__score--critical {
  background: color-mix(in srgb, var(--bad-bg) 55%, var(--surface));
  color: #b91c1c;
}
.risk-register-table__score--high {
  background: color-mix(in srgb, #fed7aa 45%, var(--surface));
}
.risk-register-table__score--mid {
  background: color-mix(in srgb, #fef3c7 40%, var(--surface));
}
.risk-register-table__score--low {
  background: var(--surface-2);
  color: var(--muted);
}
.risk-register-table__row--critical th {
  border-left: 3px solid #dc2626;
}

/* Lecture 19 — prioritization intro */
.prioritize-crunch__badge {
  margin: 0 0 14px;
  text-align: center;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: #b45309;
}
.prioritize-crunch__grid {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 12px;
  align-items: stretch;
  max-width: 680px;
  margin: 0 auto;
}
.prioritize-crunch__arrow {
  display: flex;
  align-items: center;
  font-size: 1.5rem;
  font-weight: 800;
  color: #93c5fd;
  padding-top: 2rem;
}
.prioritize-crunch__card {
  padding: 16px 16px 18px;
  border-radius: 14px;
  border: 1px solid var(--border);
  background: var(--surface);
  box-shadow: 0 12px 28px -20px rgba(37, 36, 80, 0.4);
}
.prioritize-crunch__card--bad { border-top: 4px solid #f43f5e; }
.prioritize-crunch__card--good { border-top: 4px solid #22c55e; }
.prioritize-crunch__card-title {
  margin: 0 0 8px;
  font-size: 14px;
  font-weight: 800;
  color: var(--heading);
}
.prioritize-crunch__stat,
.prioritize-crunch__lead {
  margin: 0 0 10px;
  font-size: 13.5px;
  line-height: 1.45;
  color: var(--text);
}
.prioritize-crunch__list {
  margin: 0;
  padding-left: 1.15rem;
  font-size: 13.5px;
  line-height: 1.5;
  color: var(--muted);
}
.prioritize-crunch__list--ok { color: var(--text); }
.prioritize-crunch__lesson {
  margin: 14px auto 0;
  max-width: 40rem;
  text-align: center;
  font-size: 14px;
  line-height: 1.5;
  color: var(--muted);
}
@media (max-width: 640px) {
  .prioritize-crunch__grid { grid-template-columns: 1fr; }
  .prioritize-crunch__arrow {
    justify-content: center;
    padding: 0;
    transform: rotate(90deg);
  }
}

/* Lecture 19 — execution order */
.exec-order__intro {
  margin-bottom: 12px;
  text-align: center;
}
.exec-order__badge {
  display: inline-block;
  margin-bottom: 6px;
  padding: 3px 10px;
  border-radius: 999px;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  background: color-mix(in srgb, #6366f1 14%, var(--surface-2));
  color: #4f46e5;
}
.exec-order__title {
  margin: 0 0 4px;
  font-size: 1.15rem;
  font-weight: 800;
  color: var(--heading);
}
.exec-order__subtitle {
  margin: 0;
  font-size: 12.5px;
  line-height: 1.45;
  color: var(--muted);
}
.exec-order__list {
  margin: 0 auto;
  padding: 0;
  list-style: none;
  max-width: 36rem;
  counter-reset: run;
}
.exec-order__step {
  position: relative;
  margin: 0 0 8px;
  padding: 10px 12px 10px 42px;
  border-radius: 12px;
  border: 1px solid var(--border);
  background: var(--surface);
  counter-increment: run;
}
.exec-order__step::before {
  content: counter(run);
  position: absolute;
  left: 12px;
  top: 10px;
  width: 22px;
  height: 22px;
  border-radius: 999px;
  display: grid;
  place-items: center;
  font-size: 11px;
  font-weight: 800;
  color: #fff;
  background: #6366f1;
}
.exec-order__step--p1 { border-left: 3px solid #dc2626; }
.exec-order__step--p2 { border-left: 3px solid #f59e0b; }
.exec-order__step--p3 { border-left: 3px solid #94a3b8; }
.exec-order__tc {
  font-size: 13.5px;
  font-weight: 800;
  color: var(--heading);
  margin-right: 8px;
}
.exec-order__pri {
  display: inline-block;
  padding: 2px 8px;
  border-radius: 999px;
  font-size: 11px;
  font-weight: 800;
  background: var(--surface-2);
  color: #6366f1;
}
.exec-order__reason {
  margin: 6px 0 0;
  font-size: 13.5px;
  line-height: 1.45;
  color: var(--muted);
}
.exec-order__footnote {
  margin: 12px 4px 0;
  text-align: center;
  font-size: 14px;
  line-height: 1.45;
  color: var(--muted);
}

/* Lecture 19 — priority table */
.priority-assign-table {
  min-width: 480px;
  font-size: 13.5px;
}
.priority-assign-table__text {
  text-align: left;
  font-weight: 600;
  font-size: 13.5px;
}
.priority-assign-table__pri {
  font-weight: 800;
  text-align: center;
}
.priority-assign-table__pri--p1 {
  background: color-mix(in srgb, #fef2f2 55%, var(--surface));
  color: #b91c1c;
}
.priority-assign-table__pri--p2 {
  background: color-mix(in srgb, #fef3c7 45%, var(--surface));
}
.priority-assign-table__pri--p3 {
  background: var(--surface-2);
  color: var(--muted);
}
.priority-assign-table__row--p1 th { border-left: 3px solid #dc2626; }
.priority-assign-table__row--p2 th { border-left: 3px solid #f59e0b; }
.priority-assign-table__row--p3 th { border-left: 3px solid #94a3b8; }

/* Lecture 20 — opening scenario (UI vs API) */
.api-gap-story__badge {
  margin: 0 0 14px;
  text-align: center;
  font-size: 11px;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: #4f46e5;
}
.api-gap-story__grid {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 12px;
  align-items: stretch;
  max-width: 680px;
  margin: 0 auto;
}
.api-gap-story__arrow {
  display: flex;
  align-items: center;
  font-size: 1.5rem;
  font-weight: 800;
  color: #93c5fd;
  padding-top: 2.5rem;
}
.api-gap-story__card {
  padding: 16px 16px 18px;
  border-radius: 14px;
  border: 1px solid var(--border);
  background: var(--surface);
  box-shadow: 0 12px 28px -20px rgba(37, 36, 80, 0.4);
}
.api-gap-story__card--ui {
  border-top: 4px solid #22c55e;
}
.api-gap-story__card--api {
  border-top: 4px solid #6366f1;
}
.api-gap-story__card-title {
  margin: 0 0 4px;
  font-size: 14px;
  font-weight: 800;
  color: var(--heading);
}
.api-gap-story__when {
  margin: 0 0 12px;
  font-size: 12px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--muted);
}
.api-gap-story__phone {
  padding: 12px 12px 14px;
  border-radius: 12px;
  background: var(--surface-2);
  border: 1px solid var(--border);
}
.api-gap-story__phone-bar {
  display: flex;
  gap: 5px;
  margin-bottom: 10px;
}
.api-gap-story__phone-bar span {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: color-mix(in srgb, var(--muted) 35%, var(--border));
}
.api-gap-story__screen-label {
  margin: 0 0 10px;
  font-size: 14px;
  font-weight: 800;
  color: var(--heading);
}
.api-gap-story__field {
  display: flex;
  justify-content: space-between;
  gap: 8px;
  padding: 8px 10px;
  margin-bottom: 6px;
  border-radius: 8px;
  background: var(--surface);
  border: 1px solid var(--border);
  font-size: 13.5px;
}
.api-gap-story__field-label {
  font-weight: 700;
  color: var(--muted);
}
.api-gap-story__field-value {
  font-weight: 600;
  color: var(--text);
  text-align: right;
}
.api-gap-story__btn {
  display: block;
  width: 100%;
  margin: 10px 0 0;
  padding: 9px 12px;
  border: 0;
  border-radius: 10px;
  background: #2563eb;
  color: #fff;
  font-size: 13.5px;
  font-weight: 800;
  font-family: inherit;
  opacity: 0.85;
}
.api-gap-story__toast {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  margin-top: 12px;
  padding: 10px 12px;
  border-radius: 10px;
  background: color-mix(in srgb, #dcfce7 50%, var(--surface));
  border: 1px solid color-mix(in srgb, #22c55e 40%, var(--border));
}
.api-gap-story__check {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 26px;
  height: 26px;
  border-radius: 50%;
  background: #22c55e;
  color: #fff;
  font-size: 14px;
  font-weight: 800;
}
.api-gap-story__toast-text {
  margin: 0;
  font-size: 14px;
  font-weight: 800;
  color: #15803d;
}
.api-gap-story__reqline {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  margin-bottom: 8px;
}
.api-gap-story__method {
  padding: 3px 8px;
  border-radius: 6px;
  font-size: 12px;
  font-weight: 800;
  color: #fff;
  background: #7c3aed;
}
.api-gap-story__path {
  font-size: 13px;
  font-weight: 600;
  color: var(--text);
  word-break: break-all;
}
.api-gap-story__status {
  margin: 0 0 8px;
  font-size: 13.5px;
  color: var(--muted);
}
.api-gap-story__status-code {
  font-weight: 800;
  color: #059669;
}
.api-gap-story__json {
  margin: 0 0 10px;
  padding: 10px 12px;
  border-radius: 10px;
  font-size: 13px;
  line-height: 1.5;
  background: color-mix(in srgb, var(--surface-2) 85%, var(--surface));
  border: 1px solid var(--border);
  color: var(--text);
  overflow-x: auto;
}
.api-gap-story__mismatch {
  margin: 0 0 8px;
  font-size: 13.5px;
  line-height: 1.45;
  color: var(--text);
}
.api-gap-story__hint {
  margin: 0;
  font-size: 13.5px;
  line-height: 1.45;
  color: var(--muted);
}
.api-gap-story__lesson {
  margin: 16px auto 0;
  max-width: 40rem;
  text-align: center;
  font-size: 14px;
  line-height: 1.5;
  color: var(--muted);
}
.api-gap-story__lesson strong {
  color: var(--heading);
}
@media (max-width: 640px) {
  .api-gap-story__grid {
    grid-template-columns: 1fr;
  }
  .api-gap-story__arrow {
    justify-content: center;
    padding: 0;
    transform: rotate(90deg);
  }
}

/* Lecture 20 — API request panel */
.api-panel__intro {
  margin-bottom: 12px;
  text-align: center;
}
.api-panel__badge {
  display: inline-block;
  margin-bottom: 6px;
  padding: 3px 10px;
  border-radius: 999px;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  background: color-mix(in srgb, #6366f1 14%, var(--surface-2));
  color: #4f46e5;
}
.api-panel__title {
  margin: 0 0 4px;
  font-size: 1.15rem;
  font-weight: 800;
  color: var(--heading);
}
.api-panel__subtitle {
  margin: 0;
  font-size: 12.5px;
  line-height: 1.45;
  color: var(--muted);
}
.api-panel__shell {
  max-width: 40rem;
  margin: 0 auto;
  border-radius: 14px;
  border: 1px solid var(--border);
  background: var(--surface);
  box-shadow: 0 12px 28px -20px rgba(37, 36, 80, 0.4);
  overflow: hidden;
}
.api-panel__bar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  padding: 10px 12px;
  background: var(--surface-2);
  border-bottom: 1px solid var(--border);
}
.api-panel__method {
  padding: 4px 10px;
  border-radius: 8px;
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 0.04em;
  color: #fff;
}
.api-panel__method--get { background: #059669; }
.api-panel__method--post { background: #2563eb; }
.api-panel__method--put { background: #d97706; }
.api-panel__method--patch { background: #7c3aed; }
.api-panel__method--delete { background: #dc2626; }
.api-panel__url {
  font-size: 13.5px;
  font-weight: 600;
  color: var(--text);
  word-break: break-all;
}
.api-panel__req-id {
  margin: 0;
  padding: 6px 12px 0;
  font-size: 13px;
  font-weight: 700;
  color: var(--muted);
}
.api-panel__split {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0;
}
@media (max-width: 640px) {
  .api-panel__split { grid-template-columns: 1fr; }
}
.api-panel__col {
  padding: 12px 14px 14px;
  border-right: 1px solid var(--border);
}
.api-panel__col:last-child { border-right: none; }
@media (max-width: 640px) {
  .api-panel__col {
    border-right: none;
    border-bottom: 1px solid var(--border);
  }
  .api-panel__col:last-child { border-bottom: none; }
}
.api-panel__col-title {
  margin: 0 0 8px;
  font-size: 11px;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--muted);
}
.api-panel__code {
  margin: 0;
  padding: 10px 12px;
  border-radius: 10px;
  background: color-mix(in srgb, var(--surface-2) 80%, var(--surface));
  border: 1px solid var(--border);
  font-size: 13px;
  line-height: 1.5;
  color: var(--text);
  overflow-x: auto;
}
.api-panel__code--muted {
  color: var(--muted);
}
.api-panel__status {
  margin: 0 0 8px;
  font-size: 14px;
  font-weight: 800;
}
.api-panel__status--ok { color: #059669; }
.api-panel__status--created { color: #2563eb; }
.api-panel__status--client { color: #d97706; }
.api-panel__status--server { color: #dc2626; }
.api-panel__note {
  margin: 8px 0 0;
  font-size: 11.5px;
  line-height: 1.45;
  color: var(--muted);
}
.api-panel__footnote {
  margin: 12px 4px 0;
  text-align: center;
  font-size: 12.5px;
  line-height: 1.45;
  color: var(--muted);
}

/* Lecture 20 — status code families */
.status-families__intro {
  margin-bottom: 12px;
  text-align: center;
}
.status-families__badge {
  display: inline-block;
  margin-bottom: 6px;
  padding: 3px 10px;
  border-radius: 999px;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  background: color-mix(in srgb, #0ea5e9 12%, var(--surface-2));
  color: #0369a1;
}
.status-families__title {
  margin: 0 0 4px;
  font-size: 1.15rem;
  font-weight: 800;
  color: var(--heading);
}
.status-families__subtitle {
  margin: 0;
  font-size: 12.5px;
  line-height: 1.45;
  color: var(--muted);
}
.status-families__list {
  max-width: 36rem;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.status-families__row {
  display: grid;
  grid-template-columns: 56px 1fr;
  gap: 12px;
  align-items: start;
  padding: 10px 12px;
  border-radius: 12px;
  border: 1px solid var(--border);
  background: var(--surface);
}
.status-families__digit {
  font-size: 15px;
  font-weight: 800;
  color: var(--heading);
}
.status-families__name {
  margin: 0 0 4px;
  font-size: 14px;
  font-weight: 800;
  color: var(--heading);
}
.status-families__desc {
  margin: 0 0 4px;
  font-size: 13.5px;
  line-height: 1.45;
  color: var(--muted);
}
.status-families__codes {
  margin: 0;
  font-size: 13px;
  font-weight: 700;
  line-height: 1.45;
  color: var(--text);
}
.status-families__row--ok { border-left: 3px solid #22c55e; }
.status-families__row--redirect { border-left: 3px solid #38bdf8; }
.status-families__row--client { border-left: 3px solid #f59e0b; }
.status-families__row--server { border-left: 3px solid #ef4444; }
.status-families__footnote {
  margin: 12px 4px 0;
  text-align: center;
  font-size: 12.5px;
  line-height: 1.45;
  color: var(--muted);
}

.checkout-story__badge {
  margin: 0 0 14px;
  text-align: center;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: #b45309;
}
.checkout-story__grid {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 12px;
  align-items: stretch;
  max-width: 640px;
  margin: 0 auto;
}
.checkout-story__arrow {
  display: flex;
  align-items: center;
  font-size: 1.5rem;
  font-weight: 800;
  color: #93c5fd;
  padding-top: 2rem;
}
.checkout-story__card {
  padding: 16px 16px 18px;
  border-radius: 14px;
  border: 1px solid var(--border);
  background: var(--surface);
  box-shadow: 0 12px 28px -20px rgba(37, 36, 80, 0.4);
}
.checkout-story__card--ui {
  border-top: 4px solid #22c55e;
}
.checkout-story__card--impact {
  border-top: 4px solid #f43f5e;
}
.checkout-story__card-title {
  margin: 0 0 4px;
  font-size: 13px;
  font-weight: 800;
  color: var(--heading);
}
.checkout-story__when {
  margin: 0 0 12px;
  font-size: 11px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--muted);
}
.checkout-story__confirm {
  text-align: center;
  padding: 14px 10px;
  border-radius: 12px;
  background: color-mix(in srgb, #dcfce7 45%, var(--surface-2));
  border: 1px solid color-mix(in srgb, #22c55e 35%, var(--border));
}
.checkout-story__check {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: #22c55e;
  color: #fff;
  font-size: 1.25rem;
  font-weight: 800;
  margin-bottom: 8px;
}
.checkout-story__headline {
  margin: 0 0 6px;
  font-size: 13px;
  font-weight: 800;
  line-height: 1.35;
  color: var(--heading);
}
.checkout-story__sub {
  margin: 0 0 10px;
  font-size: 12px;
  color: var(--muted);
}
.checkout-story__fake-receipt {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 8px 10px;
  border-radius: 8px;
  background: var(--surface);
  font-size: 12px;
  color: var(--muted);
}
.checkout-story__fake-receipt strong {
  color: #16a34a;
  font-weight: 800;
}
.checkout-story__impacts {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 8px;
}
.checkout-story__impact {
  display: flex;
  align-items: flex-start;
  gap: 8px;
  padding: 10px 10px;
  border-radius: 10px;
  font-size: 12.5px;
  font-weight: 600;
  line-height: 1.4;
  background: color-mix(in srgb, #ffe4e6 40%, var(--surface-2));
  border: 1px solid color-mix(in srgb, #f43f5e 30%, var(--border));
  color: var(--text);
}
.checkout-story__impact-icon {
  flex-shrink: 0;
  width: 18px;
  height: 18px;
  border-radius: 6px;
  background: #f43f5e;
  color: #fff;
  font-size: 12px;
  font-weight: 800;
  display: inline-flex;
  align-items: center;
  justify-content: center;
}
.checkout-story__cause {
  margin: 12px 0 0;
  font-size: 11.5px;
  line-height: 1.45;
  color: var(--muted);
}
.checkout-story__lesson {
  margin: 16px auto 0;
  max-width: 36rem;
  text-align: center;
  font-size: 13px;
  line-height: 1.5;
  color: var(--muted);
}
.checkout-story__lesson strong {
  color: var(--heading);
}
@media (max-width: 640px) {
  .checkout-story__grid {
    grid-template-columns: 1fr;
  }
  .checkout-story__arrow {
    justify-content: center;
    padding: 0;
    transform: rotate(90deg);
  }
}

.compare-table-wrap {
  max-width: 100%;
}
.compare-table-wrap--cards .compare-table__title {
  font-size: clamp(1.2rem, 2.5vw, 1.45rem);
}
.compare-table-wrap--cards .compare-table__subtitle {
  font-size: 15px;
  max-width: 40rem;
  margin-left: auto;
  margin-right: auto;
}
.compare-table-wrap--cards .compare-table__footnote {
  font-size: 14px;
}
.compare-table__title {
  margin: 0 0 8px;
  font-size: 1rem;
  font-weight: 800;
  color: var(--heading);
  text-align: center;
}
.compare-table__subtitle {
  margin: 0 0 18px;
  font-size: 13px;
  line-height: 1.45;
  color: var(--muted);
  text-align: center;
}
.compare-cards {
  display: grid;
  gap: 14px;
  max-width: 40rem;
  margin: 0 auto;
}
.compare-card {
  border-radius: 16px;
  border: 1px solid var(--border);
  background: var(--surface);
  box-shadow: 0 14px 32px -22px rgba(37, 36, 80, 0.4);
  overflow: hidden;
}
.compare-card__head {
  padding: 14px 18px 12px;
  border-bottom: 1px solid var(--border);
  background: color-mix(in srgb, var(--surface-2) 70%, var(--surface));
}
.compare-card--error .compare-card__head {
  border-left: 5px solid #3b82f6;
  background: linear-gradient(90deg, color-mix(in srgb, #dbeafe 55%, var(--surface)) 0%, var(--surface) 28%);
}
.compare-card--defect .compare-card__head {
  border-left: 5px solid #8b5cf6;
  background: linear-gradient(90deg, color-mix(in srgb, #ede9fe 55%, var(--surface)) 0%, var(--surface) 28%);
}
.compare-card--failure .compare-card__head {
  border-left: 5px solid #f43f5e;
  background: linear-gradient(90deg, color-mix(in srgb, #ffe4e6 50%, var(--surface)) 0%, var(--surface) 28%);
}
.compare-card__term {
  margin: 0;
  font-size: 1.2rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  color: var(--heading);
}
.compare-card__body {
  padding: 16px 18px 18px;
  display: grid;
  gap: 14px;
}
.compare-card__label {
  display: block;
  margin-bottom: 6px;
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--muted);
}
.compare-card__text {
  margin: 0;
  font-size: 16px;
  line-height: 1.55;
  color: var(--text);
  font-weight: 500;
}
.compare-card__block--example {
  padding: 12px 14px;
  border-radius: 12px;
  background: var(--surface-2);
  border: 1px dashed color-mix(in srgb, var(--border) 80%, var(--muted));
}
.compare-card__text--example {
  font-size: 15px;
  font-weight: 600;
  color: var(--heading);
}
.compare-table__scroll {
  overflow-x: auto;
  border-radius: 12px;
  border: 1px solid var(--border);
  box-shadow: 0 10px 24px -18px rgba(37, 36, 80, 0.35);
}
.compare-table {
  width: 100%;
  min-width: 520px;
  border-collapse: collapse;
  font-size: 13px;
  line-height: 1.45;
  background: var(--surface);
}
.compare-table thead th {
  padding: 12px 14px;
  text-align: left;
  font-size: 11px;
  font-weight: 800;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--muted);
  background: color-mix(in srgb, var(--surface-2) 90%, var(--border));
  border-bottom: 1px solid var(--border);
}
.compare-table tbody th {
  padding: 12px 14px;
  text-align: left;
  font-weight: 800;
  color: var(--heading);
  white-space: nowrap;
  vertical-align: top;
  border-bottom: 1px solid var(--border);
  background: var(--surface);
}
.compare-table td {
  padding: 12px 14px;
  vertical-align: top;
  color: var(--text);
  border-bottom: 1px solid var(--border);
}
.compare-table tbody tr:last-child th,
.compare-table tbody tr:last-child td {
  border-bottom: 0;
}
.compare-table tbody tr.compare-table__row--error th {
  border-left: 4px solid #3b82f6;
}
.compare-table tbody tr.compare-table__row--defect th {
  border-left: 4px solid #8b5cf6;
}
.compare-table tbody tr.compare-table__row--failure th {
  border-left: 4px solid #f43f5e;
}
.compare-table__footnote {
  margin: 10px 4px 0;
  font-size: 12px;
  line-height: 1.45;
  color: var(--muted);
  text-align: center;
}

/* knowledge check */
.kc-q {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 14px 18px;
  margin: 14px 0 8px;
  box-shadow: var(--shadow);
}
.kc-q p { margin: 6px 0 0; font-weight: 600; color: var(--text); }
.kc-num {
  display: inline-block;
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--accent);
}
.kc-a { margin: 8px 0 14px; padding-left: 14px; border-left: 3px solid var(--ok); }
.answers {
  margin: 22px 0;
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 10px 18px;
}
.answers summary { cursor: pointer; font-weight: 700; padding: 6px 0; }
.answers > div { margin-top: 8px; }

/* navigation */
.lecture-nav {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  max-width: 740px;
  margin-top: 40px;
}
.nav-card {
  display: block;
  padding: 14px 16px;
  border-radius: 14px;
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text);
  text-decoration: none;
  font-weight: 700;
}
.nav-card span {
  display: block;
  font-size: 12px;
  font-weight: 600;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 2px;
}
.nav-card.next { text-align: right; }
.nav-card:hover { border-color: var(--accent); }

/* outline (sidebar) */
.outline .sec-label {
  display: block;
  padding: 6px 8px;
  font-weight: 700;
  font-size: 13.5px;
  color: var(--text);
}
.outline:not(.outline--player) li.item.current a { color: var(--accent); font-weight: 700; background: var(--surface-2); }
.outline li.item a { font-size: 12.5px; }

/* index page */
.index-list li { margin: 4px 0; }

/* ---------- mobile ---------- */
@media (max-width: 860px) {
  .lecture { font-size: 16px; }
  .lecture-hero h1 { font-size: 26px; }
  .sec-head h2 { font-size: 20px; }
  .lecture-nav { grid-template-columns: 1fr; }
  .nav-card.next { text-align: left; }
  .kv-key { display: block; min-width: 0; margin-bottom: 2px; }
  .sub-step { grid-template-columns: 28px minmax(0, 1fr); gap: 10px; padding: 12px; }
  .step-badge { width: 26px; height: 26px; font-size: 13px; }
  .visual-header { padding: 12px 14px 8px; }
  .visual-canvas { padding: 8px 6px 12px; }
}

/* Keep the reading column inside the viewport on every screen size */
.layout > main { min-width: 0; }
.lecture * { max-width: 100%; }

/* ---------- lecture blocks inside section pages ---------- */
.lecture-block {
  scroll-margin-top: 24px;
  padding: 28px 0 8px;
  border-top: 1px solid var(--border);
}
.lecture-block:first-of-type { border-top: 0; padding-top: 12px; }
.lecture-block .lecture-hero { border-bottom: 0; padding-bottom: 6px; }
.lecture-block .lecture-title { font-size: 28px; line-height: 1.22; letter-spacing: -0.01em; margin: 0 0 8px; }
/* Quoted tester / stakeholder questions in lecture prose */
.lecture-key-question {
  display: block;
  margin: 14px 0 12px;
  padding: 14px 16px 14px 14px;
  border-radius: 14px;
  border: 1px solid color-mix(in srgb, var(--accent) 35%, var(--border));
  border-left: 4px solid var(--accent);
  background: linear-gradient(
    135deg,
    color-mix(in srgb, var(--accent) 10%, var(--surface)),
    color-mix(in srgb, var(--accent) 4%, var(--surface-2))
  );
  box-shadow: 0 10px 24px -18px color-mix(in srgb, var(--accent) 45%, transparent);
}
.concept p .lecture-key-question,
.step p .lecture-key-question,
.l1-section > p .lecture-key-question {
  margin: 16px 0;
}
.lecture-key-question__icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 26px;
  height: 26px;
  margin-right: 10px;
  border-radius: 8px;
  font-size: 15px;
  font-weight: 800;
  color: #fff;
  background: var(--brand-gradient, linear-gradient(135deg, #6366f1, #8b5cf6));
  vertical-align: middle;
  flex-shrink: 0;
}
.lecture-key-question__text {
  font-size: 1.0625rem;
  line-height: 1.5;
  font-weight: 700;
  font-style: italic;
  color: var(--heading);
  vertical-align: middle;
}
@media (min-width: 640px) {
  .lecture-key-question {
    display: flex;
    align-items: flex-start;
    gap: 4px;
    padding: 16px 18px;
  }
  .lecture-key-question__text {
    font-size: 1.125rem;
    flex: 1;
  }
}

.lecture-body { margin-top: 6px; }
.lecture-block .lecture-body > .lesson-section:first-child { margin-top: 26px; }

/* quiz panel at the end of each lecture */
.quiz-panel {
  margin: 36px 0 0;
  padding: 18px 20px 20px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 16px;
  box-shadow: var(--shadow);
}
.quiz-panel > h3 { margin: 0 0 4px; font-size: 18px; }
.quiz-head { display: flex; flex-wrap: wrap; gap: 10px; align-items: center; justify-content: space-between; margin: 8px 0 4px; }
.quiz-head .meta { color: var(--muted); font-size: 13.5px; }
.quiz-actions { display: flex; gap: 8px; }
.quiz .q { padding: 12px 0; border-bottom: 1px solid var(--border); }
.quiz .q:last-child { border-bottom: 0; }
.quiz .q > p { margin: 0 0 8px; font-weight: 600; color: var(--text); }
.quiz .q label { display: flex; gap: 8px; align-items: flex-start; padding: 6px 8px; border-radius: 8px; cursor: pointer; color: var(--text); }
.quiz .q label:hover { background: var(--surface-2); }
.quiz .q label.right { background: var(--ok-bg); color: var(--ok); }
.quiz .q label.wrong { background: var(--bad-bg); color: var(--bad); }
.quiz .verdict { font-size: 13px; margin-top: 4px; color: var(--muted); }
.score { margin: 10px 0; padding: 10px 14px; border-radius: 10px; background: var(--surface-2); font-weight: 700; }
.empty-note { color: var(--muted); font-size: 14px; font-style: italic; }
.item-card { margin-top: 28px; }

/* Landing page layout: theme.css. Shared checklist and section hero below. */
.checklist { list-style: none; padding: 0; margin: 0; background: var(--surface); border: 1px solid var(--border); border-radius: 16px; }
.checklist li { padding: 12px 16px; border-bottom: 1px solid var(--border); }
.checklist li:last-child { border-bottom: 0; }
.checklist label { display: flex; gap: 10px; align-items: center; cursor: pointer; }
.checklist input { width: 18px; height: 18px; accent-color: var(--accent); }
.benefit-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 14px; }
.benefit { border-top: 3px solid var(--accent); padding-top: 12px; }
.benefit h3 { margin: 0 0 4px; font-size: 16px; }
.benefit p { margin: 0; color: var(--muted); font-size: 14.5px; line-height: 1.55; }
.path-links { display: flex; flex-direction: column; gap: 4px; margin-top: auto; padding-top: 8px; }
.path-links a { font-size: 14px; font-weight: 600; color: var(--accent); text-decoration: none; }
.path-links a:hover { text-decoration: underline; }

/* keyboard focus, visible on every interactive element */
a:focus-visible, button:focus-visible, input:focus-visible, summary:focus-visible {
  outline: 3px solid var(--accent);
  outline-offset: 2px;
  border-radius: 6px;
}

@media (prefers-reduced-motion: reduce) {
  * { scroll-behavior: auto !important; transition: none !important; animation: none !important; }
}

@media (max-width: 860px) {
  .section-hero h1 { font-size: 26px; }
  .lecture-block .lecture-title { font-size: 24px; }
  .quiz-panel { padding: 14px 14px 16px; }
}

/* ---------- skip link, catalog search, curriculum ---------- */
.skip-link {
  position: absolute;
  left: 12px;
  top: -60px;
  z-index: 100;
  padding: 10px 14px;
  border-radius: 10px;
  background: var(--accent);
  color: var(--accent-text);
  font-weight: 700;
  text-decoration: none;
}
.skip-link:focus { top: 12px; }

.search-panel {
  display: grid;
  grid-template-columns: minmax(0, 2fr) minmax(0, 1fr);
  gap: 12px 16px;
  align-items: end;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 16px 18px;
  box-shadow: var(--shadow);
  margin-bottom: 14px;
}
.search-panel .field { display: flex; flex-direction: column; gap: 6px; min-width: 0; }
.search-panel label { font-size: 13px; font-weight: 700; color: var(--muted); }
.search-panel input, .search-panel select {
  font: inherit;
  font-size: 15px;
  padding: 10px 12px;
  border-radius: 10px;
  border: 1px solid var(--border);
  background: var(--bg);
  color: var(--text);
  width: 100%;
}
.search-panel input:focus-visible, .search-panel select:focus-visible { border-color: var(--accent); }
.search-count { grid-column: 1 / -1; margin: 0; font-size: 13.5px; color: var(--muted); }
.search-results {
  grid-column: 1 / -1;
  list-style: none;
  margin: 0;
  padding: 0;
  border-top: 1px solid var(--border);
}
.search-results li {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 4px 12px;
  padding: 10px 0;
  border-bottom: 1px solid var(--border);
  margin: 0;
}
.search-results li:last-child { border-bottom: 0; }
.search-results a { font-weight: 600; color: var(--accent); text-decoration: none; }
.search-results a:hover { text-decoration: underline; }
.result-section { font-size: 13px; color: var(--muted); }
.search-panel .empty-note { grid-column: 1 / -1; margin: 0; }

.curriculum-panel {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 18px 20px;
  box-shadow: var(--shadow);
  margin: 6px 0 8px;
}
.curriculum-panel h2 { margin: 0 0 4px; font-size: 18px; }
.curriculum-panel .lead { margin: 0 0 10px; color: var(--muted); font-size: 14px; }
.curriculum { margin: 0; padding: 0; list-style: none; counter-reset: cur; }
.curriculum li {
  counter-increment: cur;
  display: flex;
  justify-content: space-between;
  gap: 4px 12px;
  flex-wrap: wrap;
  padding: 8px 0 8px 36px;
  position: relative;
  border-top: 1px solid var(--border);
  margin: 0;
}
.curriculum li::before {
  content: counter(cur);
  position: absolute;
  left: 0;
  top: 9px;
  width: 26px;
  height: 26px;
  border-radius: 8px;
  display: grid;
  place-items: center;
  background: var(--surface-2);
  color: var(--accent);
  font-size: 12.5px;
  font-weight: 700;
}
.curriculum a { font-weight: 600; color: var(--text); text-decoration: none; }
.curriculum a:hover { color: var(--accent); text-decoration: underline; }
.curriculum .meta { font-size: 13px; color: var(--muted); }

@media (max-width: 860px) {
  .search-panel { grid-template-columns: minmax(0, 1fr); }
}

/* ---------- collapsible sidebar ---------- */
.outline-head { display: flex; align-items: center; justify-content: space-between; gap: 8px; margin-bottom: 6px; }
.outline-head h2 { margin: 0; }
.btn.small { padding: 5px 11px; font-size: 12.5px; }
.outline-sections { list-style: none; margin: 0; padding: 0; }
.outline-section { margin-bottom: 4px; }
.sec-row { display: flex; align-items: center; gap: 4px; }
.sec-row .sec { flex: 1; min-width: 0; }
.sec-toggle {
  flex: 0 0 auto;
  width: 28px;
  height: 28px;
  border: 0;
  border-radius: 8px;
  background: transparent;
  color: var(--muted);
  cursor: pointer;
  display: grid;
  place-items: center;
}
.sec-toggle:hover { background: var(--surface-2); color: var(--text); }
.sec-toggle .chevron { display: inline-block; transition: transform 160ms ease; font-size: 13px; }
.outline-section.open > .sec-row .chevron { transform: rotate(90deg); }
.sec-items[hidden] { display: none; }
.layout.side-collapsed { grid-template-columns: minmax(0, 1fr); }
.layout.side-collapsed > .outline { display: none; }
@media (max-width: 860px) {
  .layout.side-collapsed { grid-template-columns: minmax(0, 1fr); }
}
.layout.side-collapsed .menu-toggle { display: inline-block; }

/* ---------- Lecture 1 style, applied to every lecture ---------- */
.lecture-block .lecture-hero {
  position: relative;
  overflow: hidden;
  isolation: isolate;
  border: 1px solid var(--border);
  border-radius: 26px;
  padding: 34px 34px 30px;
  margin-bottom: 26px;
  background:
    radial-gradient(640px 320px at 0% 0%, rgba(124, 92, 255, 0.28), transparent 65%),
    radial-gradient(520px 300px at 100% 100%, rgba(34, 211, 238, 0.18), transparent 60%),
    var(--surface);
  box-shadow: var(--shadow-lift);
}
.lecture-block .lecture-hero .eyebrow {
  display: inline-flex;
  padding: 6px 13px;
  border-radius: 999px;
  background: var(--brand-soft);
  border: 1px solid color-mix(in srgb, var(--accent) 25%, transparent);
  font-size: 12px;
  margin: 0 0 14px;
}
.lecture-block .lecture-title {
  font-size: clamp(28px, 4vw, 40px);
  line-height: 1.14;
  letter-spacing: -0.03em;
  max-width: 22ch;
  background: linear-gradient(90deg, var(--text), var(--accent));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.lecture-block .lecture-hero .meta .chip { background: var(--surface-2); }
.lecture-block { padding-top: 34px; }
.sec-head h3 { font-size: 22px; }
.sec-num { width: 36px; height: 36px; border-radius: 12px; }
.step-badge { background: var(--brand-gradient); color: #ffffff; border: 0; box-shadow: 0 8px 18px -8px rgba(79, 70, 229, 0.7); }
.sub-step { padding: 18px 20px; }
.objectives li { border-radius: 16px; }

/* key takeaways as a card grid */
.takeaways {
  list-style: none;
  padding: 0;
  margin: 14px 0 18px;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 12px;
  counter-reset: tk;
}
.takeaways li {
  counter-increment: tk;
  position: relative;
  padding: 14px 16px 14px 56px;
  margin: 0;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 16px;
  box-shadow: var(--shadow);
  font-size: 15.5px;
  line-height: 1.6;
}
.takeaways li::before {
  content: counter(tk);
  position: absolute;
  left: 14px;
  top: 14px;
  width: 26px;
  height: 26px;
  border-radius: 999px;
  display: grid;
  place-items: center;
  background: var(--ok-bg);
  color: var(--ok);
  font-weight: 800;
  font-size: 13px;
}
.takeaways li:hover { transform: translateY(-2px); box-shadow: var(--shadow-lift); transition: transform 200ms ease, box-shadow 200ms ease; }
@media (prefers-reduced-motion: reduce) { .takeaways li:hover { transform: none; } }
@media (max-width: 860px) {
  .lecture-block .lecture-hero { padding: 26px 22px 24px; border-radius: 22px; }
  .takeaways { grid-template-columns: minmax(0, 1fr); }
}

/* Figure blocks — minimum readable sizes (overrides per-component 10–12px rules) */
.visual .visual-canvas [class*="__badge"] {
  font-size: 11px;
}
.visual .visual-canvas [class*="__subtitle"],
.visual .visual-canvas [class*="__footnote"],
.visual .visual-canvas [class*="__lesson"],
.visual .visual-canvas .dual-pillar__footnote,
.visual .visual-canvas .decision-table-wrap__footnote,
.visual .visual-canvas .status-families__footnote,
.visual .visual-canvas .api-panel__footnote,
.visual .visual-canvas .exec-order__footnote {
  font-size: 14px;
  line-height: 1.5;
}
.visual .visual-canvas [class*="__desc"],
.visual .visual-canvas [class*="__reason"],
.visual .visual-canvas [class*="__lead"],
.visual .visual-canvas [class*="__stat"],
.visual .visual-canvas [class*="__note"],
.visual .visual-canvas [class*="__req-id"],
.visual .visual-canvas [class*="__url"],
.visual .visual-canvas [class*="__codes"],
.visual .visual-canvas [class*="__text"],
.visual .visual-canvas [class*="__list"],
.visual .visual-canvas pre,
.visual .visual-canvas [class*="__code"],
.visual .visual-canvas .decision-table td,
.visual .visual-canvas .decision-table tbody th {
  font-size: 13.5px;
  line-height: 1.5;
}
.visual .visual-canvas .decision-table__colsub,
.visual .visual-canvas .decision-table__section th,
.visual .visual-canvas .decision-table__rowid {
  font-size: 11.5px;
}

/* Lecture 34: Playwright illustration inside a figure frame. */
.playwright-figure {
  padding: 12px;
}
.playwright-figure img {
  display: block;
  width: 100%;
  height: auto;
  border-radius: 12px;
}

/* Lecture 42: full Page Object Model picture inside a figure frame. */
.pom-figure {
  padding: 12px;
}
.pom-figure img {
  display: block;
  width: 100%;
  height: auto;
  border-radius: 12px;
}