:root {
  --lacquer: #120e0b;
  --paper: #f3ead9;
  --paper-2: #e9dcc6;
  --ink: #221910;
  --ink-soft: #4a3b2d;
  --muted: #7a6754;
  --cinnabar: #b4332a;
  --cinnabar-deep: #8d261f;
  --gold: #8d6b32;
  --line: #d9c7aa;
  --board: #e8c98a;
  --board-line: #6b4124;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

html { scroll-behavior: smooth; }

body {
  min-height: 100vh;
  color: var(--ink);
  font-family: "PingFang SC", "Noto Sans CJK SC", "Source Han Sans SC", "Microsoft YaHei", sans-serif;
  background:
    radial-gradient(900px 480px at 12% -10%, rgba(180, 51, 42, .28), transparent 60%),
    radial-gradient(700px 420px at 100% 0%, rgba(141, 107, 50, .18), transparent 55%),
    var(--lacquer);
}

a { color: inherit; }

.sheet {
  width: min(1120px, calc(100% - 32px));
  margin: 22px auto 36px;
  background:
    linear-gradient(90deg, rgba(141, 38, 31, .08), transparent 28px),
    var(--paper);
  border-radius: 2px 16px 16px 2px;
  box-shadow:
    0 1px 0 rgba(255, 236, 210, .35) inset,
    0 24px 70px rgba(0, 0, 0, .45);
  position: relative;
  overflow: hidden;
}

.sheet::before {
  content: "";
  position: absolute;
  left: 0; top: 0; bottom: 0;
  width: 18px;
  background:
    repeating-linear-gradient(
      to bottom,
      transparent 0 34px,
      rgba(243, 234, 217, .95) 34px 46px,
      transparent 46px 72px
    ),
    linear-gradient(#9d2b24, #7d1f1a);
}

.top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  padding: 22px 40px 18px 46px;
  border-bottom: 1px solid var(--line);
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  text-decoration: none;
}

.seal {
  width: 42px;
  height: 42px;
  display: grid;
  place-items: center;
  color: #f6efe4;
  background: var(--cinnabar);
  border: 2px solid #7d1f1a;
  box-shadow: inset 0 0 0 2px rgba(246, 239, 228, .35);
  font-family: "Noto Serif CJK SC", "Source Han Serif SC", "Songti SC", "STSong", "SimSun", serif;
  font-size: 22px;
  letter-spacing: 0;
}

.brand strong {
  display: block;
  font-family: "Noto Serif CJK SC", "Source Han Serif SC", "Songti SC", "STSong", "SimSun", serif;
  font-size: 20px;
  font-weight: 700;
  letter-spacing: .12em;
}

.brand em {
  display: block;
  margin-top: 2px;
  font-style: normal;
  font-size: 12px;
  letter-spacing: .08em;
  color: var(--muted);
}

.nav {
  display: flex;
  gap: 8px;
}

.nav a {
  text-decoration: none;
  font-size: 14px;
  color: var(--ink-soft);
  padding: 7px 12px;
  border-radius: 999px;
}

.nav a:hover { background: rgba(180, 51, 42, .08); color: var(--cinnabar-deep); }
.nav a[aria-current="page"] { color: var(--cinnabar-deep); font-weight: 600; }

.hero.solo { grid-template-columns: 1fr; }
.hero {
  display: grid;
  grid-template-columns: 1.15fr .85fr;
  gap: 28px;
  padding: 48px 48px 36px 46px;
  align-items: center;
}

.eyebrow {
  font-size: 13px;
  letter-spacing: .22em;
  color: var(--cinnabar);
  margin-bottom: 14px;
}

h1 {
  font-family: "Noto Serif CJK SC", "Source Han Serif SC", "Songti SC", "STSong", "SimSun", serif;
  font-size: 46px;
  font-weight: 700;
  line-height: 1.25;
  letter-spacing: .04em;
}

.lead {
  margin-top: 18px;
  max-width: 38em;
  font-size: 16.5px;
  line-height: 1.85;
  color: var(--ink-soft);
}

.actions {
  display: flex;
  gap: 12px;
  margin-top: 28px;
  flex-wrap: wrap;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 132px;
  height: 44px;
  padding: 0 18px;
  text-decoration: none;
  border-radius: 4px;
  font-size: 15px;
  letter-spacing: .08em;
}

.btn.primary {
  background: var(--cinnabar);
  color: #f8f1e6;
  box-shadow: 0 8px 18px rgba(141, 38, 31, .22);
}

.btn.primary:hover { background: var(--cinnabar-deep); }

.btn.ghost {
  color: var(--ink);
  border: 1px solid #c9b496;
  background: transparent;
}

.btn.ghost:hover { border-color: var(--cinnabar); color: var(--cinnabar-deep); }

.hero-side {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
}

.board-card {
  width: min(100%, 340px);
  background: linear-gradient(#f7e7c4, var(--board));
  border: 1px solid #c4a15a;
  border-radius: 10px;
  padding: 14px 14px 10px;
  box-shadow: 0 16px 36px rgba(70, 40, 12, .16);
}

.board-card svg { width: 100%; height: auto; display: block; }

.board-caption {
  display: flex;
  justify-content: space-between;
  margin-top: 8px;
  font-size: 12px;
  letter-spacing: .06em;
  color: var(--board-line);
}

.board-caption b {
  font-family: "Noto Serif CJK SC", "Source Han Serif SC", "Songti SC", serif;
  font-weight: 700;
}

.note {
  font-size: 12.5px;
  color: var(--muted);
  letter-spacing: .04em;
}

.section {
  padding: 8px 48px 42px 46px;
}

.section h2 {
  font-family: "Noto Serif CJK SC", "Source Han Serif SC", "Songti SC", "STSong", "SimSun", serif;
  font-size: 28px;
  font-weight: 700;
  letter-spacing: .08em;
}

.prose {
  margin-top: 12px;
  max-width: 40em;
  font-size: 16.5px;
  line-height: 1.85;
  color: var(--ink-soft);
}

.ecco-block { scroll-margin-top: 12px; }
.lead a { color: var(--cinnabar-deep); }
.catalog .row { color: inherit; }

.section .sub {
  margin-top: 8px;
  color: var(--muted);
  font-size: 14.5px;
  line-height: 1.7;
}

.pillars {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 14px;
  margin-top: 22px;
}

.pillar {
  background: rgba(255, 252, 246, .55);
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 18px 18px 16px;
  min-height: 168px;
}

.pillar .idx {
  font-family: "Noto Serif CJK SC", "Source Han Serif SC", "Songti SC", serif;
  color: var(--cinnabar);
  font-size: 13px;
  letter-spacing: .16em;
}

.pillar h3 {
  margin-top: 8px;
  font-family: "Noto Serif CJK SC", "Source Han Serif SC", "Songti SC", serif;
  font-size: 22px;
  font-weight: 700;
}

.pillar p {
  margin-top: 8px;
  color: var(--ink-soft);
  font-size: 14.5px;
  line-height: 1.75;
}

.catalog {
  margin-top: 18px;
  border-top: 1px solid var(--line);
}

.row {
  display: grid;
  grid-template-columns: 64px minmax(0, 1fr) auto;
  gap: 16px;
  align-items: center;
  padding: 16px 4px;
  border-bottom: 1px solid var(--line);
  text-decoration: none;
}

.row:hover { background: rgba(180, 51, 42, .05); }

.letter {
  width: 48px;
  height: 48px;
  display: grid;
  place-items: center;
  border: 1.5px solid var(--cinnabar);
  color: var(--cinnabar);
  font-family: "Noto Serif CJK SC", "Source Han Serif SC", "Songti SC", serif;
  font-size: 24px;
  font-weight: 700;
}

.row h3 {
  font-family: "Noto Serif CJK SC", "Source Han Serif SC", "Songti SC", serif;
  font-size: 20px;
  font-weight: 700;
}

.row .range {
  margin-top: 3px;
  font-size: 12.5px;
  color: var(--muted);
  letter-spacing: .04em;
}

.tags { color: var(--ink-soft); font-size: 14.5px; line-height: 1.7; text-align: right; }

.steps {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 14px;
  margin-top: 22px;
}

.step {
  padding: 18px 16px 8px;
  border-left: 2px solid var(--cinnabar);
  background: rgba(255, 252, 246, .45);
}

.step b {
  display: block;
  font-family: "Noto Serif CJK SC", "Source Han Serif SC", "Songti SC", serif;
  font-size: 18px;
  margin-bottom: 6px;
}

.step span {
  display: block;
  color: var(--ink-soft);
  font-size: 14.5px;
  line-height: 1.75;
}

.enter {
  margin-top: 26px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 16px 18px;
  background: #2a211b;
  color: #f6efe4;
  border-radius: 10px;
}

.enter p { font-size: 14.5px; line-height: 1.7; color: #e6d7c2; }
.enter strong {
  display: block;
  margin-bottom: 2px;
  font-family: "Noto Serif CJK SC", "Source Han Serif SC", "Songti SC", serif;
  font-size: 18px;
  color: #fff8ee;
  letter-spacing: .06em;
}

.foot {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
  padding: 18px 40px 22px 46px;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 12.5px;
  line-height: 1.7;
}

.foot a { color: var(--cinnabar-deep); }
.friends { display: flex; align-items: center; gap: 14px; flex-wrap: wrap; }
.friends span { letter-spacing: .12em; }

.switch, .decade-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 16px;
}

.switch a, .decade-nav a {
  text-decoration: none;
  color: var(--cinnabar-deep);
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 4px 12px;
  background: rgba(255, 252, 246, .55);
}

.switch a[aria-current="page"] {
  color: #fff8ee;
  background: var(--cinnabar);
  border-color: var(--cinnabar);
}

.decade-nav a { border-radius: 6px; font-size: 14px; }

.code { padding: 14px 0; border-bottom: 1px solid var(--line); scroll-margin-top: 12px; }

.code-head {
  display: grid;
  grid-template-columns: 64px minmax(0, 1fr) auto;
  gap: 12px;
  align-items: baseline;
}

.code-id {
  font-family: "Noto Serif CJK SC", "Source Han Serif SC", "Songti SC", serif;
  font-weight: 700;
  color: var(--cinnabar);
  letter-spacing: .04em;
}

.code h3 {
  font-family: "Noto Serif CJK SC", "Source Han Serif SC", "Songti SC", serif;
  font-size: 18px;
  font-weight: 700;
}

.code .formula {
  display: block;
  color: var(--muted);
  font-size: 12.5px;
  letter-spacing: .04em;
}

.moves { margin: 6px 0 0 76px; color: var(--ink-soft); font-size: 15px; line-height: 1.75; }
.moves p { margin: 0; }

.code.is-empty {
  display: grid;
  grid-template-columns: 64px 1fr;
  align-items: center;
  padding: 8px 0;
  color: var(--muted);
}

.code.is-empty h3 { font-size: 15px; font-weight: 500; color: var(--muted); }

.empty-list {
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  gap: 8px;
  margin-top: 14px;
  list-style: none;
}

.empty-list li {
  border: 1px solid var(--line);
  border-radius: 6px;
  padding: 8px 10px;
  color: var(--muted);
  scroll-margin-top: 12px;
}

.empty-list span {
  display: block;
  color: var(--cinnabar);
  font-family: "Noto Serif CJK SC", "Source Han Serif SC", "Songti SC", serif;
  font-weight: 700;
}

@media (max-width: 860px) {
  .sheet { width: min(100% - 16px, 1120px); margin: 8px auto 20px; }
  .top, .hero, .section, .foot { padding-left: 28px; padding-right: 18px; }
  .hero, .pillars, .steps { grid-template-columns: 1fr; }
  .row { grid-template-columns: 56px 1fr; }
  .tags { grid-column: 2; }
  .code-head { grid-template-columns: 56px 1fr; }
  .code .tags, .code .formula { text-align: left; }
  .moves { margin-left: 0; }
  .empty-list { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  h1 { font-size: 34px; }
  .enter { flex-direction: column; align-items: flex-start; }
  .nav a { padding: 6px 8px; }
}