/* =========================================================
   Yiwen Gao · Personal Style Guide
   Keel-format layout, original palette & fonts.
   ========================================================= */

:root {
  /* Color tokens */
  --color-sage:       #9A9D88;
  --color-mint:       #C8F0C5;
  --color-cream:      #F0F3E5;
  --color-cream-warm: #F5F6EB;
  --color-sand:       #DDD4BD;
  --color-soft-sage:  #B8C7A8;
  --color-brown:      #3D2E1F;
  --color-ink:        #3A3A30;
  --color-muted:      #6F6F5C;
  --color-line:       rgba(58, 58, 48, 0.14);

  /* Dark mode overrides (applied via [data-mode="dark"]) */
  --bg:         var(--color-cream);
  --bg-raised:  var(--color-cream-warm);
  --fg:         var(--color-ink);
  --fg-muted:   var(--color-muted);
  --border:     var(--color-line);

  /* Type tokens */
  --font-serif: 'Cardo', 'Iowan Old Style', Georgia, serif;
  --font-sans:  'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono:  'DM Mono', ui-monospace, 'SF Mono', Menlo, monospace;

  /* Spacing tokens */
  --space-1: 4px;
  --space-2: 8px;
  --space-3: 16px;
  --space-4: 24px;
  --space-5: 40px;
  --space-6: 80px;
  --space-7: 120px;

  /* Border radius */
  --radius-sm:   4px;
  --radius-md:   8px;
  --radius-pill: 999px;

  /* Layout */
  --header-h:   48px;
  --sidebar-w:  240px;
  --toc-w:      220px;
  --content-max: 780px;
}

/* Dark mode ------------------------------------------------ */
[data-mode="dark"] {
  --bg:         #1C1C18;
  --bg-raised:  #242420;
  --fg:         #D8D8C8;
  --fg-muted:   #8A8A74;
  --border:     rgba(200, 200, 180, 0.12);
  --color-sage: #7D8070;
}

/* ---------- Reset ----------------------------------------- */
*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: var(--font-sans);
  font-size: 15px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}
a { color: inherit; text-decoration: none; }
button { font: inherit; cursor: pointer; border: none; background: none; }
img, svg { display: block; }
p { margin: 0 0 var(--space-3); }
ul { margin: 0; padding-left: var(--space-5); }

/* ---------- Site Header ------------------------------------ */
.site-header {
  position: fixed;
  top: 0; left: 0; right: 0;
  height: var(--header-h);
  background: var(--color-sage);
  color: var(--color-mint);
  display: flex;
  align-items: center;
  gap: var(--space-5);
  padding: 0 var(--space-5);
  z-index: 100;
  border-bottom: 1px solid rgba(0,0,0,0.08);
}
.sh-brand {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  flex-shrink: 0;
}
.sh-tri  { font-size: 9px; opacity: .7; }
.sh-name { font: 600 13px/1 var(--font-sans); letter-spacing: 0.2em; text-transform: uppercase; }
.sh-badge {
  font: 500 11px/1 var(--font-mono);
  background: rgba(200, 240, 197, 0.18);
  border: 1px solid rgba(200, 240, 197, 0.3);
  color: var(--color-mint);
  padding: 2px 7px;
  border-radius: var(--radius-pill);
  letter-spacing: 0.04em;
}
.sh-nav {
  display: flex;
  gap: var(--space-4);
  align-items: center;
  flex: 1;
}
.sh-nav a {
  font: 500 13px/1 var(--font-sans);
  color: rgba(200, 240, 197, 0.72);
  letter-spacing: 0.03em;
  transition: color 150ms;
}
.sh-nav a:hover { color: var(--color-mint); }
.sh-actions { margin-left: auto; }
.theme-toggle {
  width: 32px; height: 32px;
  border-radius: var(--radius-pill);
  display: flex; align-items: center; justify-content: center;
  color: rgba(200, 240, 197, 0.72);
  transition: background 150ms, color 150ms;
}
.theme-toggle:hover { background: rgba(200, 240, 197, 0.14); color: var(--color-mint); }
.icon-moon { display: none; }
[data-mode="dark"] .icon-sun  { display: none; }
[data-mode="dark"] .icon-moon { display: block; }

/* ---------- Three-pane shell ------------------------------ */
.sidebar {
  position: fixed;
  top: var(--header-h);
  left: 0;
  width: var(--sidebar-w);
  height: calc(100vh - var(--header-h));
  background: var(--color-sage);
  color: var(--color-mint);
  overflow-y: auto;
  z-index: 50;
  border-right: 1px solid rgba(0,0,0,0.06);
}
.sidebar-scroll { padding: var(--space-4) 0 var(--space-6); }

.doc-main {
  margin-left: var(--sidebar-w);
  margin-right: var(--toc-w);
  padding: var(--space-7) var(--space-6);
  padding-top: calc(var(--header-h) + var(--space-6));
  min-height: 100vh;
}

.toc-panel {
  position: fixed;
  top: var(--header-h);
  right: 0;
  width: var(--toc-w);
  height: calc(100vh - var(--header-h));
  overflow-y: auto;
  padding: var(--space-5) var(--space-4);
  border-left: 1px solid var(--border);
}

/* ---------- Sidebar nav ----------------------------------- */
.nav-group { border-bottom: 1px solid rgba(200, 240, 197, 0.1); }
.nav-group-btn {
  width: 100%;
  display: flex; align-items: center; justify-content: space-between;
  padding: var(--space-3) var(--space-4);
  font: 600 11px/1 var(--font-sans);
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: rgba(200, 240, 197, 0.55);
  transition: color 150ms;
}
.nav-group-btn:hover { color: rgba(200, 240, 197, 0.85); }
.chevron {
  color: rgba(200, 240, 197, 0.4);
  flex-shrink: 0;
  transition: transform 200ms ease;
}
.nav-group-btn[aria-expanded="false"] .chevron { transform: rotate(-90deg); }

.nav-group-items {
  overflow: hidden;
  transition: max-height 220ms ease;
}
.nav-group-btn[aria-expanded="false"] + .nav-group-items {
  max-height: 0 !important;
}

.nav-link {
  display: block;
  font: 400 14px/1.4 var(--font-serif);
  color: rgba(200, 240, 197, 0.72);
  padding: 7px var(--space-4);
  border-left: 2px solid transparent;
  margin-left: var(--space-3);
  transition: color 150ms, border-color 150ms;
}
.nav-link:hover { color: rgba(200, 240, 197, 0.95); }
.nav-link.is-active {
  color: var(--color-mint);
  border-left-color: var(--color-mint);
  font-style: italic;
}

/* ---------- TOC panel ------------------------------------- */
.toc-label {
  font: 600 11px/1 var(--font-sans);
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--fg-muted);
  margin-bottom: var(--space-3);
}
.toc-nav { display: flex; flex-direction: column; gap: 2px; }
.toc-link {
  display: block;
  font: 400 13px/1.4 var(--font-sans);
  color: var(--fg-muted);
  padding: 5px var(--space-2);
  border-left: 1px solid var(--border);
  transition: color 150ms, border-color 150ms;
}
.toc-link:hover { color: var(--fg); }
.toc-link.is-active { color: var(--color-sage); border-left-color: var(--color-sage); }
.toc-link--h3 { padding-left: var(--space-4); font-size: 12px; }

/* ---------- Doc sections ---------------------------------- */
.doc-section {
  max-width: var(--content-max);
  padding-bottom: var(--space-7);
  border-bottom: 1px solid var(--border);
  margin-bottom: var(--space-7);
  scroll-margin-top: calc(var(--header-h) + var(--space-5));
}
.doc-section:last-child { border-bottom: none; margin-bottom: 0; }
.doc-section--last { padding-bottom: var(--space-7); }

.doc-section-header { margin-bottom: var(--space-6); }
.doc-kicker {
  display: inline-block;
  font: 600 11px/1 var(--font-sans);
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--fg-muted);
  margin-bottom: var(--space-3);
}
.doc-title {
  font: 700 clamp(40px, 6vw, 72px)/0.96 var(--font-serif);
  letter-spacing: -0.015em;
  text-transform: uppercase;
  margin: 0 0 var(--space-4);
  color: var(--fg);
}
.doc-lead {
  font-size: 17px;
  line-height: 1.55;
  color: var(--fg-muted);
  max-width: 58ch;
  margin: 0;
}
.doc-h2 {
  font: 600 13px/1 var(--font-sans);
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--fg-muted);
  margin: var(--space-6) 0 var(--space-4);
  padding-bottom: var(--space-3);
  border-bottom: 1px solid var(--border);
}

/* ---------- Hero section ---------------------------------- */
.doc-section--hero {
  padding-bottom: var(--space-7);
  min-height: 90vh;
  display: flex;
  flex-direction: column;
  justify-content: center;
}
.hero-display {
  font: 700 clamp(72px, 14vw, 180px)/0.88 var(--font-serif);
  letter-spacing: -0.03em;
  text-transform: uppercase;
  color: var(--color-soft-sage);
  margin: 0 0 var(--space-5);
}
.hero-meta {
  font: 600 12px/1 var(--font-sans);
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--fg-muted);
  display: flex;
  align-items: center;
  gap: var(--space-3);
  margin-bottom: var(--space-6);
}
.hero-year { margin-left: auto; font-family: var(--font-mono); letter-spacing: 0.05em; }
.tri { color: var(--color-sage); font-size: 9px; }
.doc-lead-block { max-width: 58ch; margin-bottom: var(--space-6); }
.doc-lead-block .doc-lead { margin-bottom: var(--space-3); color: var(--fg); font-size: 19px; }
.doc-body-muted { font-size: 15px; color: var(--fg-muted); margin: 0; }

.intro-meta-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-4);
  border-top: 1px solid var(--border);
  padding-top: var(--space-5);
}
.intro-meta-cell { }
.imc-label { font: 600 11px/1 var(--font-sans); letter-spacing: 0.18em; text-transform: uppercase; color: var(--fg-muted); margin-bottom: var(--space-2); }
.imc-value { font: 400 15px/1.4 var(--font-serif); color: var(--fg); }

/* ---------- Principles ------------------------------------ */
.ns-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1px;
  background: var(--border);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  overflow: hidden;
  margin-bottom: var(--space-6);
}
.ns-card {
  background: var(--bg-raised);
  padding: var(--space-5);
}
.ns-word {
  font: 400 italic 28px/1.1 var(--font-serif);
  color: var(--fg-muted);
  margin-bottom: var(--space-3);
}
.ns-card p { color: var(--fg); margin: 0; font-size: 14px; line-height: 1.55; }

.value-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-5);
}
.value-card {
  padding-left: var(--space-3);
  border-left: 2px solid var(--color-sage);
}
.vc-title {
  font: 600 12px/1.2 var(--font-sans);
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--fg);
  margin-bottom: var(--space-2);
}
.value-card p { margin: 0; color: var(--fg-muted); font-size: 14px; }

/* ---------- Color swatches -------------------------------- */
.swatch-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-3);
  margin-bottom: var(--space-6);
}
.swatch-grid--sm { grid-template-columns: repeat(3, 1fr); }
.swatch-card {
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  overflow: hidden;
  background: var(--bg-raised);
}
.sc-chip {
  height: 120px;
  border-bottom: 1px solid var(--border);
}
.sc-chip--sm { height: 72px; }
.sc-body { padding: var(--space-3); }
.sc-name { font: 600 14px/1.2 var(--font-sans); color: var(--fg); margin-bottom: var(--space-1); }
.sc-token { font: 400 12px/1 var(--font-mono); color: var(--color-sage); margin-bottom: 4px; }
.sc-hex  { font: 400 12px/1 var(--font-mono); color: var(--fg-muted); margin-bottom: var(--space-2); }
.sc-use  { font-size: 13px; color: var(--fg-muted); margin: 0; line-height: 1.4; }

/* ---------- Callouts -------------------------------------- */
.callout {
  padding: var(--space-3) var(--space-4);
  background: var(--color-mint);
  color: var(--color-brown);
  border-left: 3px solid var(--color-sage);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  font-size: 14px;
  margin-bottom: var(--space-4);
  line-height: 1.5;
}
.callout--sand { background: var(--color-sand); }
.callout strong { font-weight: 600; }

/* ---------- Typeface cards -------------------------------- */
.typeface-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-3);
  margin-bottom: var(--space-6);
}
.typeface-card {
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: var(--space-5);
  background: var(--bg-raised);
}
.tf-label { font: 600 11px/1 var(--font-sans); letter-spacing: 0.2em; text-transform: uppercase; color: var(--fg-muted); margin-bottom: var(--space-3); }
.tf-name  { font-size: 32px; line-height: 1; color: var(--fg); margin-bottom: var(--space-3); }
.tf-desc  { font-size: 13px; color: var(--fg-muted); margin-bottom: var(--space-4); line-height: 1.5; }
.tf-weights { display: flex; flex-direction: column; gap: 4px; border-top: 1px solid var(--border); padding-top: var(--space-3); font-size: 13px; color: var(--fg-muted); }

/* ---------- Type scale ------------------------------------ */
.type-scale { border: 1px solid var(--border); border-radius: var(--radius-sm); overflow: hidden; margin-bottom: var(--space-6); }
.ts-row {
  display: grid;
  grid-template-columns: 90px 120px 160px 1fr;
  align-items: center;
  gap: var(--space-3);
  padding: var(--space-3) var(--space-4);
  border-bottom: 1px solid var(--border);
}
.ts-row:last-child { border-bottom: none; }
.ts-row--head {
  background: var(--bg-raised);
  font: 600 11px/1 var(--font-sans);
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--fg-muted);
}
.ts-tag {
  display: inline-block;
  font: 500 11px/1 var(--font-mono);
  background: var(--bg-raised);
  border: 1px solid var(--border);
  padding: 3px 7px;
  border-radius: var(--radius-pill);
  color: var(--color-sage);
}
.ts-val  { font: 400 13px/1 var(--font-mono); color: var(--fg-muted); }
.ts-fam  { font: 400 13px/1 var(--font-sans); color: var(--fg-muted); }
.ts-preview { color: var(--fg); }
.ts-mono { font-family: var(--font-mono); font-size: 12px; color: var(--color-sage); }

/* ---------- Spacing table --------------------------------- */
.sp-table { border: 1px solid var(--border); border-radius: var(--radius-sm); overflow: hidden; margin-bottom: var(--space-6); }
.sp-row {
  display: grid;
  grid-template-columns: 160px 80px 160px 1fr;
  align-items: center;
  gap: var(--space-3);
  padding: var(--space-3) var(--space-4);
  border-bottom: 1px solid var(--border);
}
.sp-row:last-child { border-bottom: none; }
.sp-row--head {
  background: var(--bg-raised);
  font: 600 11px/1 var(--font-sans);
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--fg-muted);
}
.sp-name { font-size: 14px; color: var(--fg); }
.sp-vis { display: flex; align-items: center; }
.sp-vis > div { height: 20px; background: var(--color-sage); border-radius: 2px; }

/* ---------- Principle cards ------------------------------- */
.principle-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-4);
  margin-bottom: var(--space-6);
}
.principle-card { padding: var(--space-5); background: var(--bg-raised); border: 1px solid var(--border); border-radius: var(--radius-sm); }
.pc-num { font: 500 11px/1 var(--font-mono); color: var(--color-sage); margin-bottom: var(--space-3); letter-spacing: 0.06em; }
.principle-card h3 { font: 400 20px/1.3 var(--font-serif); color: var(--fg); margin: 0 0 var(--space-3); }
.principle-card p  { margin: 0; font-size: 14px; color: var(--fg-muted); }

/* ---------- Token table ----------------------------------- */
.token-table { border: 1px solid var(--border); border-radius: var(--radius-sm); overflow: hidden; margin-bottom: var(--space-6); }
.tt-row {
  display: grid;
  grid-template-columns: 220px 200px 1fr;
  align-items: center;
  gap: var(--space-3);
  padding: var(--space-3) var(--space-4);
  border-bottom: 1px solid var(--border);
  font-size: 14px;
}
.tt-row:last-child { border-bottom: none; }
.tt-head {
  background: var(--bg-raised);
  font: 600 11px/1 var(--font-sans);
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--fg-muted);
}

/* ---------- Component demos ------------------------------- */
.comp-demo {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-3);
  padding: var(--space-5);
  background: var(--bg-raised);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  margin-bottom: var(--space-5);
}
.comp-demo--padded { padding: var(--space-6); }
.comp-demo--dark { background: var(--color-sand); }
.comp-demo--grid { display: grid; grid-template-columns: 1fr 1fr; }

/* ---------- Code blocks ----------------------------------- */
.code-block {
  background: #2A2A24;
  color: #C8C8A8;
  font: 400 13px/1.65 var(--font-mono);
  padding: var(--space-4);
  border-radius: var(--radius-sm);
  overflow-x: auto;
  margin: 0 0 var(--space-5);
  white-space: pre;
}
code {
  font: 400 13px/1.5 var(--font-mono);
  background: var(--bg-raised);
  border: 1px solid var(--border);
  padding: 2px 6px;
  border-radius: 3px;
  color: var(--color-sage);
}
.code-block code {
  background: none;
  border: none;
  padding: 0;
  color: inherit;
}

/* ---------- Buttons --------------------------------------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  font: 500 14px/1 var(--font-sans);
  padding: 10px 20px;
  border-radius: var(--radius-pill);
  border: 1px solid transparent;
  letter-spacing: 0.02em;
  transition: transform 120ms ease, background 180ms ease, border-color 180ms ease, color 180ms ease, box-shadow 180ms ease;
  white-space: nowrap;
  position: relative;
  overflow: hidden;
  cursor: pointer;
  color: var(--fg);
}
.btn:active { transform: scale(0.98); }

/* Color variants */
.btn-primary { background: var(--color-sage); color: var(--color-mint); }
.btn-primary:hover { background: #898C78; }
.btn-mint    { background: var(--color-mint); color: #3D5A36; }
.btn-mint:hover { background: #B9E5B5; }
.btn-sand    { background: var(--color-sand); color: var(--color-brown); }
.btn-sand:hover { background: #D0C6AC; }
.btn-brown   { background: var(--color-brown); color: var(--color-cream); }
.btn-brown:hover { background: #2E2114; }
.btn-ghost   { background: transparent; color: var(--fg); border-color: var(--border); }
.btn-ghost:hover { border-color: var(--color-sage); background: var(--bg-raised); }
.btn-outline { background: transparent; color: var(--color-sage); border-color: var(--color-sage); }
.btn-outline:hover { background: var(--color-sage); color: var(--color-mint); }

/* Shape variants */
.btn-pill    { border-radius: var(--radius-pill); }
.btn-rounded { border-radius: var(--radius-md); }
.btn-square  { border-radius: 0; }
.btn-circle  {
  border-radius: 50%;
  width: 40px; height: 40px;
  padding: 0;
}

/* Size variants */
.btn-sm { padding: 6px 14px; font-size: 12px; }
.btn-lg { padding: 14px 28px; font-size: 16px; }

/* Text link (legacy variant) */
.btn-link {
  font: 500 14px/1 var(--font-sans);
  color: var(--color-sage);
  border-bottom: 1px solid var(--color-sage);
  padding-bottom: 2px;
  display: inline-block;
  transition: color 150ms;
}
.btn-link:hover { color: var(--color-brown); border-bottom-color: var(--color-brown); }

/* ---------- Button animations ----------------------------- */

/* Lift on hover */
.btn-lift { transition: transform 240ms cubic-bezier(.2,.8,.2,1), box-shadow 240ms ease, background 180ms; }
.btn-lift:hover { transform: translateY(-3px); box-shadow: 0 8px 24px rgba(61,46,31,0.18); }
.btn-lift:active { transform: translateY(-1px); }

/* Arrow slide */
.btn-arrow .btn-arrow-icon {
  display: inline-block;
  transition: transform 220ms cubic-bezier(.4,.0,.2,1);
}
.btn-arrow:hover .btn-arrow-icon { transform: translateX(6px); }

/* Shimmer sweep */
.btn-shimmer::before {
  content: "";
  position: absolute;
  top: 0;
  left: -100%;
  width: 60%;
  height: 100%;
  background: linear-gradient(110deg, transparent 30%, rgba(255,255,255,0.35) 50%, transparent 70%);
  transition: left 700ms cubic-bezier(.4,.0,.2,1);
  pointer-events: none;
}
.btn-shimmer:hover::before { left: 160%; }

/* Fill from left */
.btn-fill { position: relative; isolation: isolate; }
.btn-fill::before {
  content: "";
  position: absolute;
  inset: 0;
  background: var(--color-sage);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 320ms cubic-bezier(.4,.0,.2,1);
  z-index: -1;
}
.btn-fill > span { position: relative; z-index: 1; transition: color 220ms; }
.btn-fill:hover::before { transform: scaleX(1); }
.btn-fill:hover > span { color: var(--color-mint); }

/* 3D press */
.btn-press {
  box-shadow: 0 4px 0 rgba(61,46,31,0.5);
  transition: transform 100ms ease, box-shadow 100ms ease, background 180ms;
}
.btn-press:hover { transform: translateY(-1px); box-shadow: 0 5px 0 rgba(61,46,31,0.5); }
.btn-press:active { transform: translateY(2px); box-shadow: 0 2px 0 rgba(61,46,31,0.5); }

/* Underline grow */
.btn-underline { position: relative; padding-left: 0; padding-right: 0; background: none; border: none; border-radius: 0; }
.btn-underline::after {
  content: "";
  position: absolute;
  bottom: 4px;
  left: 50%;
  width: 0;
  height: 1.5px;
  background: var(--color-sage);
  transition: width 240ms ease, left 240ms ease;
}
.btn-underline:hover::after { width: 100%; left: 0; }

/* ---------- Pull quote ------------------------------------ */
.pull-quote {
  margin: 0;
  font: 400 22px/1.55 var(--font-serif);
  color: var(--fg);
  position: relative;
  padding-left: var(--space-5);
  max-width: 54ch;
}
.pq-mark {
  position: absolute;
  left: -8px; top: -24px;
  font: 700 100px/1 var(--font-serif);
  color: var(--color-sage);
  opacity: 0.5;
}
.pull-quote cite {
  display: block;
  margin-top: var(--space-3);
  font: 500 12px/1 var(--font-sans);
  font-style: normal;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--fg-muted);
}

/* ---------- Signature pattern demos ----------------------- */
.pattern-cropped-demo {
  width: 100%;
  overflow: hidden;
  position: relative;
}
.pcd-bg {
  font: 700 clamp(60px, 12vw, 140px)/0.88 var(--font-serif);
  text-transform: uppercase;
  color: rgba(154, 157, 136, 0.28);
  letter-spacing: -0.02em;
  margin-top: -28px;
  line-height: 0.88;
}
.pcd-body { color: var(--fg-muted); font-size: 14px; margin-top: var(--space-4); }

.byline {
  font: 600 12px/1 var(--font-sans);
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--fg-muted);
  display: flex; align-items: center; gap: 6px;
}

.what-if-demo .wi-pre { font: 400 italic 22px/1 var(--font-serif); color: var(--fg-muted); margin-bottom: var(--space-4); }
.what-if-demo .wi-q   { font: 700 36px/1.2 var(--font-serif); color: var(--fg); max-width: 16ch; }

/* ---------- Visual Components (shapes) -------------------- */
.shape-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-3);
  margin-bottom: var(--space-6);
}
.shape-card {
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  overflow: hidden;
  background: var(--bg-raised);
  display: flex;
  flex-direction: column;
}
.shape-stage {
  height: 160px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--color-cream);
  border-bottom: 1px solid var(--border);
}
.shape-stage svg { display: block; }
.shape-meta { padding: var(--space-3) var(--space-4) var(--space-4); }
.shape-name { font: 600 14px/1.2 var(--font-sans); color: var(--fg); margin-bottom: var(--space-1); }
.shape-token { font: 400 12px/1 var(--font-mono); color: var(--color-sage); margin-bottom: var(--space-2); }
.shape-meta p { font-size: 13px; color: var(--fg-muted); margin: 0; line-height: 1.5; }

/* Shape animations */
@keyframes rotate-slow { from { transform: rotate(0deg); } to { transform: rotate(360deg); } }
@keyframes pulse-slow {
  0%, 100% { transform: scale(1); opacity: 1; }
  50%      { transform: scale(1.12); opacity: 0.75; }
}
@keyframes float-y {
  0%, 100% { transform: translateY(0); }
  50%      { transform: translateY(-8px); }
}

.shape-card--animated .shape-stage svg { transform-origin: center; will-change: transform; }
.rotate-slow { animation: rotate-slow 40s linear infinite; transform-origin: 40px 40px; transform-box: fill-box; }
.pulse-slow  { animation: pulse-slow 3.6s ease-in-out infinite; transform-origin: 40px 40px; transform-box: fill-box; }
.float       { animation: float-y 6s ease-in-out infinite; }

.shape-card--animated:hover .rotate-slow { animation-duration: 8s; }
.shape-card--animated:hover .pulse-slow,
.shape-card--animated:hover .float       { animation-duration: 1.6s; }

/* ---------- Rule list ------------------------------------- */
.rule-list { list-style: none; padding: 0; margin-bottom: var(--space-6); }
.rule-list li {
  padding: var(--space-3) 0;
  border-bottom: 1px solid var(--border);
  color: var(--fg-muted);
  font-size: 14px;
  line-height: 1.6;
}
.rule-list li:last-child { border-bottom: none; }
.rule-list strong { color: var(--fg); font-family: var(--font-serif); font-size: 16px; font-weight: 400; font-style: italic; }

/* ---------- Colophon -------------------------------------- */
.colophon-body { max-width: 54ch; }
.colophon-body p { color: var(--fg-muted); font-size: 16px; line-height: 1.7; }
.colophon-body em { font-family: var(--font-serif); font-style: italic; color: var(--fg); }
.colophon-links { display: flex; gap: var(--space-4); margin-top: var(--space-5); }

/* ---------- Mobile nav toggle ----------------------------- */
.nav-toggle {
  position: fixed;
  bottom: var(--space-4);
  right: var(--space-4);
  width: 44px; height: 44px;
  background: var(--color-sage);
  border-radius: var(--radius-pill);
  display: none;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: 4px;
  z-index: 200;
  box-shadow: 0 4px 16px rgba(0,0,0,0.12);
}
.nav-toggle span { display: block; width: 18px; height: 2px; background: var(--color-mint); border-radius: 1px; transition: transform 200ms; }

/* ---------- Responsive ------------------------------------ */
@media (max-width: 1100px) {
  .toc-panel { display: none; }
  .doc-main  { margin-right: 0; }
}

@media (max-width: 900px) {
  .sidebar {
    transform: translateX(-100%);
    transition: transform 240ms ease;
  }
  .sidebar.is-open { transform: translateX(0); }
  .doc-main { margin-left: 0; padding: calc(var(--header-h) + var(--space-5)) var(--space-4) var(--space-7); }
  .nav-toggle { display: flex; }
  .sh-nav { display: none; }

  .ns-grid { grid-template-columns: 1fr; }
  .value-grid { grid-template-columns: 1fr; }
  .swatch-grid { grid-template-columns: 1fr 1fr; }
  .typeface-grid { grid-template-columns: 1fr; }
  .ts-row { grid-template-columns: 80px 1fr; }
  .ts-row--head span:nth-child(3),
  .ts-row > *:nth-child(3) { display: none; }
  .sp-row { grid-template-columns: 140px 60px 1fr; }
  .sp-row--head span:nth-child(3),
  .sp-row > *:nth-child(3) { display: none; }
  .principle-grid { grid-template-columns: 1fr; }
  .tt-row { grid-template-columns: 1fr 1fr; }
  .tt-row--head span:nth-child(3),
  .tt-row > *:nth-child(3) { display: none; }
  .comp-demo--grid { grid-template-columns: 1fr; }
  .shape-grid { grid-template-columns: 1fr 1fr; }
  .intro-meta-grid { grid-template-columns: 1fr; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { transition: none !important; animation: none !important; }
}