:root {
  --bg: #f5efe7;
  --bg-2: #fbf8f2;
  --ink: #201917;
  --muted: #5f554d;
  --line: rgba(77, 58, 37, 0.16);
  --accent: #7d5a2a;
  --card: rgba(255, 251, 245, 0.92);
  --shadow: 0 24px 60px rgba(58, 40, 26, 0.08);
  --radius: 24px;
  --thumb-bg: #f7f1e7;
  --max: 1260px;
}
* { box-sizing: border-box; }
body {
  margin: 0;
  color: var(--ink);
  font-family: "PingFang SC", "Noto Sans SC", "Helvetica Neue", sans-serif;
  background:
    radial-gradient(circle at top left, rgba(139, 103, 52, 0.18), transparent 28%),
    linear-gradient(180deg, var(--bg), var(--bg-2));
  min-height: 100vh;
}
a { color: inherit; text-decoration: none; }
img { max-width: 100%; display: block; }
.page { width: min(calc(100% - 32px), var(--max)); margin: 0 auto; padding: 28px 0 60px; }
.topbar { position: sticky; top: 0; z-index: 20; backdrop-filter: blur(18px); background: rgba(255,248,240,0.84); border-bottom: 1px solid var(--line); }
.topbar-inner { width: min(calc(100% - 32px), var(--max)); margin: 0 auto; display: flex; justify-content: space-between; gap: 16px; padding: 14px 0; align-items: center; }
.brand { font-family: "Songti SC", "Noto Serif SC", serif; font-size: 1.1rem; font-weight: 700; letter-spacing: 0.04em; }
.nav-links { display: flex; flex-wrap: wrap; gap: 10px; }
.nav-links a, .pill { padding: 8px 14px; border-radius: 999px; border: 1px solid var(--line); background: rgba(255,255,255,0.64); color: var(--muted); font-size: 0.92rem; }
.hero, .card, .section-card, .viewer, .chapter-hero, .concept-hero, .plate-hero, .question-card, .glossary-card { background: var(--card); border: 1px solid var(--line); border-radius: var(--radius); box-shadow: var(--shadow); }
.hero, .chapter-hero, .concept-hero, .plate-hero { padding: 34px; margin-top: 24px; display: grid; gap: 14px; }
.hero h1, .chapter-hero h1, .concept-hero h1, .plate-hero h1 { margin: 0; font-family: "Songti SC", "Noto Serif SC", serif; line-height: 1.15; font-size: clamp(2rem, 4vw, 3.5rem); }
.hero p, .chapter-hero p, .concept-hero p, .plate-hero p, .section-card p, .glossary-card p { margin: 0; color: var(--muted); line-height: 1.72; }
.hero-meta, .stats, .chip-row, .actions, .thumb-strip { display: flex; flex-wrap: wrap; gap: 10px; }
.stat { min-width: 136px; padding: 16px; border-radius: 18px; background: rgba(255,255,255,0.75); border: 1px solid var(--line); }
.stat strong { display: block; font-size: 1.5rem; margin-bottom: 6px; }
.path-panel { margin-top: 18px; color: var(--muted); font-size: 0.95rem; }
.section-title { display: flex; justify-content: space-between; align-items: end; gap: 16px; margin: 36px 0 16px; }
.section-title h2 { margin: 0; font-size: 1.45rem; font-family: "Songti SC", "Noto Serif SC", serif; }
.grid { display: grid; gap: 16px; }
.grid-2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.card, .section-card, .glossary-card { padding: 18px; }
.card h3, .section-card h3, .glossary-card h3 { margin: 0 0 10px; font-size: 1.12rem; }
.eyebrow { display: inline-flex; align-items: center; gap: 8px; margin-bottom: 12px; color: var(--accent); font-weight: 600; font-size: 0.9rem; }
.chapter-layout, .concept-layout, .plate-layout { display: grid; grid-template-columns: minmax(0, 1.7fr) minmax(280px, 0.95fr); gap: 18px; align-items: start; }
.viewer { position: sticky; top: 86px; padding: 18px; display: grid; gap: 16px; }
.viewer figure, .plate-image { margin: 0; border-radius: 18px; overflow: hidden; border: 1px solid var(--line); background: var(--thumb-bg); padding: 18px; }
.viewer figure img, .plate-image img { width: 100%; height: auto; object-fit: contain; }
.thumb-button { width: 94px; border-radius: 16px; border: 1px solid var(--line); background: rgba(255,255,255,0.88); padding: 8px; cursor: pointer; }
.thumb-button img, .plate-card img, .chapter-card img, .concept-card img { width: 100%; aspect-ratio: 4 / 3; object-fit: contain; background: var(--thumb-bg); border-radius: 12px; padding: 10px; }
.thumb-button.is-active { border-color: var(--accent); box-shadow: inset 0 0 0 1px rgba(125,90,42,0.2); }
.list { margin: 0; padding-left: 18px; color: var(--muted); line-height: 1.8; }
.route-list { display: grid; gap: 12px; }
.route-item, .plate-group { border: 1px solid var(--line); border-radius: 18px; padding: 16px; background: rgba(255,255,255,0.66); display: grid; gap: 12px; }
.route-item strong, .plate-group strong { display: block; margin-bottom: 8px; }
.chapter-grid, .concept-grid, .plate-grid, .glossary-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 16px; }
.glossary-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.card { display: grid; gap: 12px; }
.question-card { padding: 20px; }
details summary { cursor: pointer; font-weight: 700; }
.footer-nav { margin-top: 26px; display: flex; justify-content: space-between; gap: 12px; flex-wrap: wrap; }
.footer-nav a { flex: 1 1 220px; padding: 14px 16px; border-radius: 18px; border: 1px solid var(--line); background: rgba(255,255,255,0.66); }
.small { font-size: 0.92rem; }
.muted { color: var(--muted); }
@media (max-width: 960px) {
  .grid-2, .chapter-grid, .concept-grid, .plate-grid, .glossary-grid, .chapter-layout, .concept-layout, .plate-layout { grid-template-columns: 1fr; }
  .viewer { position: static; }
  .hero, .chapter-hero, .concept-hero, .plate-hero { padding: 24px; }
}