:root {
  --paper: #f3eee3;
  --paper-strong: #f9f4ea;
  --ink: #16242d;
  --ink-soft: #30424d;
  --ink-muted: #667984;
  --line: rgba(22, 36, 45, 0.14);
  --line-strong: rgba(22, 36, 45, 0.24);
  --panel: rgba(249, 244, 234, 0.82);
  --panel-strong: rgba(255, 251, 243, 0.95);
  --panel-ink: #11202a;
  --copper: #a4693c;
  --copper-soft: #e4c6a4;
  --teal: #0d8b8f;
  --teal-soft: #cfecea;
  --red: #a04536;
  --green: #236c57;
  --shadow-lg: 0 24px 80px rgba(17, 32, 42, 0.14);
  --shadow-md: 0 14px 42px rgba(17, 32, 42, 0.1);
  --radius-xl: 30px;
  --radius-lg: 22px;
  --radius-md: 16px;
  --radius-sm: 12px;
  --content-width: 1480px;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-height: 100vh;
  color: var(--ink);
  font-family: "IBM Plex Sans", system-ui, sans-serif;
  background:
    radial-gradient(circle at top left, rgba(13, 139, 143, 0.16), transparent 24%),
    radial-gradient(circle at 85% 10%, rgba(164, 105, 60, 0.2), transparent 30%),
    linear-gradient(180deg, #fbf7ef 0%, #f0e8da 42%, #efe7da 100%);
  position: relative;
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  pointer-events: none;
  background-image:
    linear-gradient(rgba(22, 36, 45, 0.03) 1px, transparent 1px),
    linear-gradient(90deg, rgba(22, 36, 45, 0.03) 1px, transparent 1px),
    radial-gradient(circle at 20% 20%, rgba(255, 255, 255, 0.5), transparent 30%);
  background-size: 28px 28px, 28px 28px, auto;
  mask-image: linear-gradient(180deg, rgba(0, 0, 0, 0.92), rgba(0, 0, 0, 0.55));
  opacity: 0.9;
}

a {
  color: inherit;
}

img,
svg {
  max-width: 100%;
  display: block;
}

code,
.mono,
.metric-kicker,
.eyebrow,
.source-kind,
.toc-caption,
.section-index,
.diagram-caption strong {
  font-family: "IBM Plex Mono", ui-monospace, monospace;
}

.skip-link {
  position: absolute;
  left: 1rem;
  top: -4rem;
  padding: 0.75rem 1rem;
  border-radius: 999px;
  background: var(--ink);
  color: white;
  z-index: 200;
}

.skip-link:focus {
  top: 1rem;
}

.scroll-progress {
  position: fixed;
  inset: 0 auto auto 0;
  width: 100%;
  height: 4px;
  background: linear-gradient(90deg, var(--teal), var(--copper));
  transform: scaleX(0);
  transform-origin: left center;
  z-index: 150;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(24px);
  background: rgba(251, 247, 239, 0.72);
  border-bottom: 1px solid rgba(22, 36, 45, 0.08);
}

.site-header-inner {
  max-width: var(--content-width);
  margin: 0 auto;
  padding: 1rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.brand-lockup {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.brand-mark {
  width: 3rem;
  height: 3rem;
  border-radius: 1rem;
  display: grid;
  place-items: center;
  color: white;
  background:
    linear-gradient(135deg, rgba(13, 139, 143, 0.9), rgba(22, 36, 45, 0.95));
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.25), var(--shadow-md);
}

.brand-mark svg {
  width: 1.55rem;
  height: 1.55rem;
}

.brand-copy {
  display: grid;
  gap: 0.15rem;
}

.brand-title {
  margin: 0;
  font-family: "Space Grotesk", "IBM Plex Sans", sans-serif;
  font-size: 1.1rem;
  font-weight: 700;
  letter-spacing: -0.03em;
}

.brand-subtitle {
  margin: 0;
  color: var(--ink-muted);
  font-size: 0.88rem;
}

.topline {
  display: inline-flex;
  align-items: center;
  gap: 0.55rem;
  padding: 0.35rem 0.7rem;
  border-radius: 999px;
  border: 1px solid rgba(13, 139, 143, 0.18);
  background: rgba(13, 139, 143, 0.08);
  color: var(--teal);
  font-size: 0.74rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  font-weight: 600;
}

.global-nav-list {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 0.55rem;
  margin: 0;
  padding: 0;
}

.global-nav-link {
  display: inline-flex;
  align-items: center;
  padding: 0.72rem 1rem;
  border-radius: 999px;
  text-decoration: none;
  color: var(--ink-soft);
  border: 1px solid transparent;
  background: rgba(255, 255, 255, 0.35);
  transition: transform 160ms ease, background 160ms ease, color 160ms ease, border-color 160ms ease;
}

.global-nav-link:hover,
.global-nav-link:focus-visible {
  transform: translateY(-1px);
  background: rgba(255, 255, 255, 0.78);
  border-color: rgba(22, 36, 45, 0.08);
}

.global-nav-link.is-active {
  color: white;
  background: linear-gradient(135deg, var(--ink), #223843);
  border-color: rgba(255, 255, 255, 0.18);
  box-shadow: var(--shadow-md);
}

.page-shell {
  max-width: var(--content-width);
  margin: 0 auto;
  padding: 1.5rem;
}

.page-frame {
  display: grid;
  grid-template-columns: 240px minmax(0, 1fr) 240px;
  gap: 1.25rem;
  align-items: start;
}

.rail {
  position: sticky;
  top: 6.3rem;
  display: grid;
  gap: 1rem;
}

.rail-card {
  border-radius: var(--radius-lg);
  border: 1px solid var(--line);
  background: linear-gradient(180deg, rgba(255, 252, 246, 0.9), rgba(247, 239, 225, 0.72));
  box-shadow: var(--shadow-md);
  padding: 1rem;
}

.rail-title {
  margin: 0 0 0.55rem;
  font-size: 0.83rem;
  color: var(--ink-muted);
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.rail-copy {
  margin: 0;
  color: var(--ink-soft);
  font-size: 0.93rem;
  line-height: 1.6;
}

.chapter-stack,
.mini-list,
.toc-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 0.45rem;
}

.chapter-stack a,
.mini-list a,
.toc-link {
  display: flex;
  gap: 0.7rem;
  align-items: baseline;
  text-decoration: none;
  color: var(--ink-soft);
  padding: 0.7rem 0.8rem;
  border-radius: 14px;
  transition: background 160ms ease, color 160ms ease, transform 160ms ease;
}

.chapter-stack a:hover,
.mini-list a:hover,
.toc-link:hover,
.toc-link:focus-visible {
  color: var(--ink);
  background: rgba(255, 255, 255, 0.8);
  transform: translateX(2px);
}

.toc-link.is-active,
.chapter-stack a[aria-current="page"] {
  background: rgba(13, 139, 143, 0.12);
  color: var(--ink);
  border: 1px solid rgba(13, 139, 143, 0.12);
}

.section-index {
  color: var(--copper);
  font-size: 0.75rem;
}

.toc-caption {
  margin: 0 0 0.85rem;
  color: var(--ink-muted);
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.content-column {
  display: grid;
  gap: 1.25rem;
}

.hero-panel,
.section-card,
.diagram-card,
.data-card,
.quote-card,
.timeline-card,
.table-card,
.callout-card {
  position: relative;
  overflow: hidden;
  border-radius: var(--radius-xl);
  border: 1px solid var(--line);
  background: linear-gradient(180deg, rgba(255, 251, 243, 0.94), rgba(246, 238, 224, 0.88));
  box-shadow: var(--shadow-lg);
}

.hero-panel::before,
.section-card::before,
.diagram-card::before,
.data-card::before,
.timeline-card::before {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background:
    radial-gradient(circle at top right, rgba(228, 198, 164, 0.35), transparent 28%),
    linear-gradient(180deg, rgba(255, 255, 255, 0.35), transparent 42%);
}

.hero-panel {
  padding: 2rem;
}

.hero-kicker,
.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.45rem 0.75rem;
  border-radius: 999px;
  border: 1px solid rgba(164, 105, 60, 0.18);
  color: var(--copper);
  background: rgba(164, 105, 60, 0.08);
  font-size: 0.72rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  font-weight: 700;
}

.hero-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.2fr) minmax(320px, 0.9fr);
  gap: 1.4rem;
  align-items: end;
}

.hero-copy h1 {
  margin: 1rem 0 0.95rem;
  max-width: 10ch;
  font-family: "Space Grotesk", "IBM Plex Sans", sans-serif;
  font-size: clamp(2.5rem, 5vw, 4.9rem);
  line-height: 0.92;
  letter-spacing: -0.06em;
}

.hero-copy p {
  margin: 0;
  max-width: 60ch;
  color: var(--ink-soft);
  font-size: 1.08rem;
  line-height: 1.75;
}

.hero-actions,
.chip-row,
.metric-row,
.mobile-toc-links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.7rem;
}

.chip-link,
.key-chip {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  padding: 0.72rem 0.92rem;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.68);
  border: 1px solid rgba(22, 36, 45, 0.08);
  color: var(--ink-soft);
  text-decoration: none;
  font-size: 0.9rem;
}

.hero-stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.85rem;
}

.metric-card {
  position: relative;
  border-radius: var(--radius-lg);
  padding: 1.1rem;
  border: 1px solid rgba(22, 36, 45, 0.08);
  background: linear-gradient(180deg, rgba(17, 32, 42, 0.94), rgba(32, 52, 64, 0.96));
  color: white;
  min-height: 124px;
}

.metric-card--soft {
  background: linear-gradient(180deg, rgba(13, 139, 143, 0.13), rgba(255, 255, 255, 0.76));
  color: var(--ink);
}

.metric-value {
  margin: 0.25rem 0;
  font-family: "Space Grotesk", "IBM Plex Sans", sans-serif;
  font-size: 2rem;
  line-height: 1;
  letter-spacing: -0.05em;
}

.metric-label {
  margin: 0;
  color: inherit;
  opacity: 0.9;
  font-size: 0.92rem;
  line-height: 1.5;
}

.metric-kicker {
  color: rgba(255, 255, 255, 0.66);
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.metric-card--soft .metric-kicker {
  color: var(--ink-muted);
}

.section-card,
.diagram-card,
.data-card,
.timeline-card,
.table-card,
.callout-card {
  padding: 1.6rem;
}

.section-head {
  display: flex;
  flex-wrap: wrap;
  gap: 0.9rem;
  align-items: flex-start;
  justify-content: space-between;
  margin-bottom: 1.2rem;
}

.section-head h2 {
  margin: 0.5rem 0 0;
  font-family: "Space Grotesk", "IBM Plex Sans", sans-serif;
  font-size: clamp(1.65rem, 3vw, 2.4rem);
  line-height: 1;
  letter-spacing: -0.05em;
}

.section-head p {
  margin: 0.65rem 0 0;
  max-width: 62ch;
  color: var(--ink-soft);
  line-height: 1.72;
}

.source-badges {
  display: flex;
  flex-wrap: wrap;
  gap: 0.45rem;
}

.source-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  padding: 0.44rem 0.7rem;
  border-radius: 999px;
  font-size: 0.77rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  font-weight: 700;
}

.source-badge--prd {
  background: rgba(13, 139, 143, 0.1);
  color: var(--teal);
}

.source-badge--spec {
  background: rgba(22, 36, 45, 0.08);
  color: var(--ink-soft);
}

.source-badge--mixed {
  background: rgba(164, 105, 60, 0.1);
  color: var(--copper);
}

.prose,
.list-grid li,
.sequence-card p,
.callout-card p,
.detail-list li {
  color: var(--ink-soft);
  line-height: 1.75;
}

.columns-2,
.columns-3,
.card-grid,
.feature-grid,
.detail-grid,
.metric-grid,
.diagram-grid,
.matrix-grid {
  display: grid;
  gap: 1rem;
}

.columns-2,
.detail-grid,
.diagram-grid {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.columns-3,
.card-grid,
.feature-grid,
.metric-grid,
.matrix-grid {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.info-card,
.feature-card,
.sequence-card,
.mini-card,
.matrix-card,
.timeline-step,
.stack-card {
  position: relative;
  padding: 1rem;
  border-radius: var(--radius-lg);
  border: 1px solid rgba(22, 36, 45, 0.08);
  background: rgba(255, 255, 255, 0.64);
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.55);
}

.info-card h3,
.feature-card h3,
.sequence-card h3,
.mini-card h3,
.stack-card h3,
.matrix-card h3 {
  margin: 0 0 0.55rem;
  font-size: 1.02rem;
  line-height: 1.35;
}

.info-card p,
.feature-card p,
.sequence-card p,
.mini-card p,
.stack-card p,
.matrix-card p {
  margin: 0;
}

.icon-pill {
  width: 2.35rem;
  height: 2.35rem;
  border-radius: 0.9rem;
  display: grid;
  place-items: center;
  margin-bottom: 0.9rem;
  background: rgba(13, 139, 143, 0.12);
  color: var(--teal);
}

.icon-pill--copper {
  background: rgba(164, 105, 60, 0.12);
  color: var(--copper);
}

.signal-strip {
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  gap: 0.85rem;
}

.signal-pill {
  padding: 0.9rem;
  border-radius: var(--radius-lg);
  background: rgba(17, 32, 42, 0.92);
  color: white;
}

.signal-pill strong {
  display: block;
  font-size: 1.25rem;
  margin-top: 0.2rem;
}

.signal-pill span {
  color: rgba(255, 255, 255, 0.68);
  font-size: 0.84rem;
}

.diagram-shell {
  display: grid;
  gap: 1rem;
}

.diagram-toolbar {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
}

.diagram-toggle {
  border: 1px solid rgba(22, 36, 45, 0.08);
  background: rgba(255, 255, 255, 0.72);
  color: var(--ink-soft);
  border-radius: 999px;
  padding: 0.7rem 1rem;
  font-size: 0.9rem;
  cursor: pointer;
  transition: transform 160ms ease, background 160ms ease, color 160ms ease;
}

.diagram-toggle:hover,
.diagram-toggle:focus-visible {
  transform: translateY(-1px);
}

.diagram-toggle.is-active {
  background: linear-gradient(135deg, var(--teal), #0b6d6f);
  color: white;
  border-color: transparent;
}

.diagram-frame {
  padding: 1rem;
  border-radius: var(--radius-lg);
  background:
    linear-gradient(180deg, rgba(17, 32, 42, 0.98), rgba(25, 44, 57, 0.98)),
    radial-gradient(circle at top right, rgba(13, 139, 143, 0.2), transparent 30%);
  overflow: hidden;
}

.diagram-frame svg {
  width: 100%;
  height: auto;
}

.diagram-node {
  opacity: 0.26;
  transition: opacity 180ms ease, transform 180ms ease;
}

.diagram-node.is-active {
  opacity: 1;
}

.diagram-node.is-muted {
  opacity: 0.18;
}

.diagram-caption {
  display: grid;
  gap: 0.4rem;
  color: var(--ink-soft);
}

.diagram-caption strong {
  font-size: 0.78rem;
  color: var(--copper);
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.diagram-panel {
  display: none;
  padding: 1rem;
  border-radius: var(--radius-lg);
  border: 1px solid rgba(13, 139, 143, 0.1);
  background: rgba(13, 139, 143, 0.06);
}

.diagram-panel.is-active {
  display: block;
}

.diagram-panel h3 {
  margin: 0 0 0.55rem;
  font-size: 1rem;
}

.diagram-panel p {
  margin: 0;
  color: var(--ink-soft);
  line-height: 1.72;
}

.pill-grid {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.pill {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  padding: 0.46rem 0.7rem;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.74);
  border: 1px solid rgba(22, 36, 45, 0.08);
  color: var(--ink-soft);
  font-size: 0.82rem;
}

.pill--alert {
  color: var(--red);
  background: rgba(160, 69, 54, 0.08);
  border-color: rgba(160, 69, 54, 0.12);
}

.pill--ok {
  color: var(--green);
  background: rgba(35, 108, 87, 0.08);
  border-color: rgba(35, 108, 87, 0.12);
}

.table-wrap {
  overflow-x: auto;
  border-radius: var(--radius-lg);
  border: 1px solid rgba(22, 36, 45, 0.08);
  background: rgba(255, 255, 255, 0.66);
}

table {
  width: 100%;
  border-collapse: collapse;
  min-width: 640px;
}

th,
td {
  padding: 0.95rem 1rem;
  text-align: left;
  vertical-align: top;
  border-bottom: 1px solid rgba(22, 36, 45, 0.08);
}

th {
  color: var(--ink-muted);
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  background: rgba(255, 255, 255, 0.52);
}

td {
  color: var(--ink-soft);
  line-height: 1.65;
}

tr:last-child td {
  border-bottom: none;
}

.timeline {
  display: grid;
  gap: 0.9rem;
  position: relative;
}

.timeline::before {
  content: "";
  position: absolute;
  left: 0.85rem;
  top: 0;
  bottom: 0;
  width: 1px;
  background: linear-gradient(180deg, rgba(13, 139, 143, 0.4), rgba(164, 105, 60, 0.22));
}

.timeline-step {
  display: grid;
  grid-template-columns: 2.2rem minmax(0, 1fr);
  gap: 0.95rem;
}

.timeline-marker {
  width: 1.7rem;
  height: 1.7rem;
  border-radius: 999px;
  background: linear-gradient(135deg, var(--teal), var(--copper));
  box-shadow: 0 0 0 5px rgba(255, 255, 255, 0.86);
  margin-top: 0.1rem;
}

.timeline-step h3 {
  margin: 0 0 0.35rem;
  font-size: 1rem;
}

.timeline-step p {
  margin: 0;
}

.kpi-bar {
  display: flex;
  flex-wrap: wrap;
  gap: 0.9rem;
}

.kpi {
  flex: 1 1 180px;
  padding: 1rem;
  border-radius: var(--radius-lg);
  background: rgba(255, 255, 255, 0.68);
  border: 1px solid rgba(22, 36, 45, 0.08);
}

.kpi strong {
  display: block;
  font-family: "Space Grotesk", "IBM Plex Sans", sans-serif;
  font-size: 1.55rem;
  letter-spacing: -0.05em;
}

.kpi span {
  color: var(--ink-muted);
  font-size: 0.86rem;
}

.accordion-stack {
  display: grid;
  gap: 0.8rem;
}

details.accordion {
  border-radius: var(--radius-lg);
  border: 1px solid rgba(22, 36, 45, 0.08);
  background: rgba(255, 255, 255, 0.7);
  overflow: hidden;
}

details.accordion summary {
  cursor: pointer;
  padding: 1rem 1.1rem;
  font-weight: 600;
  list-style: none;
}

details.accordion summary::-webkit-details-marker {
  display: none;
}

details.accordion[open] summary {
  border-bottom: 1px solid rgba(22, 36, 45, 0.08);
}

.accordion-body {
  padding: 1rem 1.1rem 1.15rem;
  color: var(--ink-soft);
  line-height: 1.72;
}

.source-foot {
  margin-top: 1rem;
  padding-top: 0.95rem;
  border-top: 1px solid rgba(22, 36, 45, 0.08);
}

.source-link-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.55rem;
}

.source-link {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  text-decoration: none;
  padding: 0.58rem 0.8rem;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.72);
  border: 1px solid rgba(22, 36, 45, 0.08);
  color: var(--ink-soft);
  font-size: 0.85rem;
}

.source-link:hover,
.source-link:focus-visible {
  color: var(--ink);
  border-color: rgba(13, 139, 143, 0.18);
}

.source-kind {
  display: inline-flex;
  align-items: center;
  padding: 0.18rem 0.42rem;
  border-radius: 999px;
  background: rgba(13, 139, 143, 0.12);
  color: var(--teal);
  font-size: 0.68rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.term-button {
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
  position: relative;
  color: var(--teal);
  text-decoration: underline;
  text-decoration-style: dotted;
  text-decoration-thickness: 0.08em;
  cursor: pointer;
}

.term-button:focus-visible {
  outline: 2px solid rgba(13, 139, 143, 0.25);
  outline-offset: 2px;
  border-radius: 0.4rem;
}

.term-popover {
  position: absolute;
  left: 0;
  top: calc(100% + 0.65rem);
  z-index: 40;
  width: min(280px, 80vw);
  padding: 0.95rem;
  border-radius: 18px;
  border: 1px solid rgba(22, 36, 45, 0.08);
  background: linear-gradient(180deg, rgba(17, 32, 42, 0.98), rgba(28, 44, 56, 0.98));
  color: white;
  box-shadow: var(--shadow-md);
}

.term-popover-title {
  display: block;
  margin-bottom: 0.45rem;
}

.term-popover-copy {
  margin: 0;
  font-size: 0.92rem;
  line-height: 1.6;
  color: rgba(255, 255, 255, 0.76);
}

.term-popover-link {
  display: inline-flex;
  margin-top: 0.75rem;
  color: var(--copper-soft);
  text-decoration: none;
}

.page-footer {
  margin: 1.5rem 0 2rem;
  padding: 1.25rem 1.5rem 2rem;
  text-align: center;
  color: var(--ink-muted);
  font-size: 0.92rem;
}

.footer-link {
  color: var(--ink-soft);
}

.mobile-toc {
  display: none;
}

.legend-list,
.detail-list {
  margin: 0;
  padding-left: 1.1rem;
}

.detail-list {
  display: grid;
  gap: 0.45rem;
}

.list-grid {
  margin: 0;
  padding-left: 1rem;
  display: grid;
  gap: 0.55rem;
}

.banner-callout {
  display: grid;
  gap: 0.6rem;
  padding: 1rem 1.1rem;
  border-radius: var(--radius-lg);
  background: linear-gradient(135deg, rgba(164, 105, 60, 0.12), rgba(13, 139, 143, 0.08));
  border: 1px solid rgba(22, 36, 45, 0.08);
}

.banner-callout strong {
  font-size: 1rem;
}

.banner-callout p {
  margin: 0;
  color: var(--ink-soft);
  line-height: 1.72;
}

.stack {
  display: grid;
  gap: 0.85rem;
}

.quiet {
  color: var(--ink-muted);
}

.page-shell > * {
  animation: fadeUp 420ms ease both;
}

@keyframes fadeUp {
  from {
    opacity: 0;
    transform: translateY(12px);
  }

  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@media (max-width: 1260px) {
  .page-frame {
    grid-template-columns: 220px minmax(0, 1fr);
  }

  .rail--toc {
    display: none;
  }
}

@media (max-width: 980px) {
  .site-header-inner {
    flex-direction: column;
    align-items: flex-start;
  }

  .page-frame {
    grid-template-columns: 1fr;
  }

  .rail--chapters {
    display: none;
  }

  .mobile-toc {
    display: block;
  }

  .hero-grid,
  .columns-2,
  .columns-3,
  .card-grid,
  .feature-grid,
  .detail-grid,
  .metric-grid,
  .diagram-grid,
  .matrix-grid,
  .signal-strip {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 720px) {
  .page-shell {
    padding: 1rem;
  }

  .hero-panel,
  .section-card,
  .diagram-card,
  .data-card,
  .timeline-card,
  .table-card,
  .callout-card {
    padding: 1.2rem;
    border-radius: 24px;
  }

  .hero-copy h1 {
    max-width: 12ch;
  }

  .hero-stats {
    grid-template-columns: 1fr;
  }

  .table-wrap table {
    min-width: 540px;
  }
}