:root {
  --camphor: #2a1c14;
  --shelf: #3a2a1e;
  --silk: #efe4d0;
  --silk-2: #f7f0e2;
  --indigo: #3a4a6d;
  --zhu: #7a3144;
  --gold: #c9b48a;
  --mute: #7a6c5c;
  --ink: #1c140e;
  --serif: "Noto Serif SC", "Songti SC", serif;
  --sans: "Noto Sans SC", "PingFang SC", sans-serif;
  --mono: "IBM Plex Mono", ui-monospace, Menlo, monospace;
}
*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; }
section[id] { scroll-margin-top: 72px; }
body {
  margin: 0;
  background: var(--silk);
  color: var(--ink);
  font-family: var(--sans);
  line-height: 1.75;
}
img { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }
.app-link { color: var(--zhu); text-decoration: underline; text-underline-offset: 3px; }
button, input { font-family: inherit; }
code { font-family: var(--mono); background: rgba(122, 49, 68, 0.1); padding: 0 0.3em; }
.silk {
  pointer-events: none;
  position: fixed;
  inset: 0;
  z-index: 8;
  opacity: 0.18;
  background-image: url("images/texture.webp");
  background-size: 420px;
  mix-blend-mode: multiply;
}
.skip { position: absolute; left: -999px; }
.skip:focus { left: 12px; top: 10px; z-index: 80; background: var(--gold); padding: 8px; }

.stack-bar {
  position: sticky;
  top: 0;
  z-index: 40;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 10px 22px;
  background: var(--camphor);
  color: var(--silk);
  border-bottom: 3px solid var(--gold);
}
.brand { display: flex; align-items: center; gap: 10px; font-family: var(--serif); font-weight: 700; }
.brand small { display: block; font-family: var(--mono); font-size: 10px; letter-spacing: 0.16em; color: var(--gold); font-weight: 400; }
.han-mark {
  width: 32px; height: 32px;
  display: inline-flex; align-items: center; justify-content: center;
  border: 1px solid var(--gold);
  font-family: var(--serif);
  color: var(--gold);
}
.nav-toggle {
  display: none;
  background: transparent;
  color: var(--gold);
  border: 1px solid var(--gold);
  padding: 6px 12px;
  cursor: pointer;
}
.stack-nav { display: flex; flex-wrap: wrap; gap: 14px; font-size: 14px; }
.stack-nav a { color: #cbbba4; }
.stack-nav a.is-active, .stack-nav a:hover { color: var(--gold); }
.stack-nav .live { background: var(--gold); color: var(--camphor); padding: 5px 12px; }

.hero { position: relative; min-height: 92vh; }
.hero > img { position: absolute; inset: 0; width: 100%; height: 100%; object-fit: cover; }
.hero-copy {
  position: relative;
  z-index: 1;
  width: min(720px, calc(100% - 48px));
  margin-left: 6vw;
  margin-top: 8vh;
  margin-bottom: 8vh;
  padding: 36px 32px;
  color: var(--silk);
  background: rgba(42, 28, 20, 0.72);
  border-left: 6px solid var(--gold);
}
.kicker, .vlabel {
  font-family: var(--mono);
  letter-spacing: 0.16em;
  font-size: 11px;
  color: var(--gold);
  margin: 0 0 10px;
}
h1, h2, h3 { font-family: var(--serif); margin: 0 0 12px; line-height: 1.12; }
h1 { font-size: clamp(40px, 6vw, 76px); }
h2 { font-size: clamp(26px, 3.2vw, 40px); }
h3 { font-size: 22px; }
.lead { max-width: 40em; }
.ribbon-row { display: flex; flex-wrap: wrap; gap: 8px; margin: 18px 0 22px; }
.ribbon {
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  padding: 4px 10px;
  background: rgba(42, 28, 20, 0.55);
  border-left: 4px solid var(--gold);
}
.ribbon.zhu { border-left-color: var(--zhu); }
.ribbon.dian { border-left-color: var(--indigo); }
.ribbon.jin { border-left-color: var(--gold); }
.hero-actions { display: flex; gap: 10px; flex-wrap: wrap; }
.btn { display: inline-flex; padding: 10px 18px; border: 1px solid currentColor; }
.btn-fill { background: var(--gold); color: var(--camphor); border-color: var(--gold); }
.btn-ghost { color: var(--silk); }

.stack { width: min(1100px, calc(100% - 40px)); margin: 0 auto; padding: 80px 0; }
.stack-head { margin-bottom: 24px; }
.night-band { background: var(--camphor); color: var(--silk); }
.night-band .vlabel { color: var(--gold); }
.han-stack { display: grid; grid-template-columns: 1fr 1fr 1fr; gap: 14px; }
.slipcase {
  background: var(--silk-2);
  padding: 18px;
  border: 1px solid #d8c8a8;
  box-shadow: 6px 8px 0 rgba(42, 28, 20, 0.08);
}
.slipcase ul, .io-pair ul, .rule-list { margin: 0; padding-left: 1.15em; }

.open-row {
  display: grid;
  grid-template-columns: 1.05fr 0.95fr;
  gap: 24px;
  align-items: center;
  margin: 28px 0;
  padding: 8px 0 28px;
  border-bottom: 1px dashed rgba(201, 180, 138, 0.35);
}
.open-row.reverse { direction: rtl; }
.open-row.reverse > * { direction: ltr; }
.open-row figure { margin: 0; }
.open-row img { width: 100%; height: 240px; object-fit: cover; }
.open-row figcaption { font-size: 13px; color: var(--mute); margin-top: 8px; }
.night-band .open-row figcaption { color: #b8a890; }
.idx { font-family: var(--mono); color: var(--gold); letter-spacing: 0.14em; }
.case-toggle, .gap-dial {
  margin-top: 12px;
}
.case-toggle {
  background: transparent;
  color: var(--gold);
  border: 1px solid var(--gold);
  padding: 8px 12px;
  cursor: pointer;
}
.case-body { margin-top: 10px; padding: 12px; background: rgba(201, 180, 138, 0.12); }
.gap-dial { padding: 12px; background: rgba(201, 180, 138, 0.1); }
#gap-range { width: 100%; accent-color: var(--zhu); }
.tri-state.warn { color: #e0a070; }
.tri-state.ok { color: #8fbf8a; }
.tri-state.late { color: #e07070; }
.hash-tape {
  font-family: var(--mono);
  font-size: 12px;
  padding: 8px 10px;
  background: var(--gold);
  color: var(--camphor);
  display: inline-block;
}

.bench-slips, .value-slips { display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; }
.bench-slips article, .value-slips article {
  padding: 16px;
  background: var(--silk-2);
  border-top: 4px solid var(--gold);
}
.night-band .value-slips article { background: var(--shelf); }
.rule-list { background: var(--silk-2); padding: 18px 18px 18px 38px; border-left: 8px solid var(--zhu); }
.io-pair { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }
.io-pair > div { background: var(--shelf); padding: 18px; }
footer { padding: 22px 28px 40px; font-size: 13px; color: var(--mute); }

@media (max-width: 900px) {
  .han-stack, .open-row, .open-row.reverse, .bench-slips, .value-slips, .io-pair { grid-template-columns: 1fr; direction: ltr; }
  .hero-copy { margin-left: 20px; padding-top: 8vh; }
  .nav-toggle { display: inline-block; }
  .stack-bar { flex-wrap: wrap; position: relative; }
  .stack-nav {
    display: none;
    width: 100%;
    flex-direction: column;
    background: var(--shelf);
    padding: 12px;
    border: 1px solid var(--gold);
  }
  .stack-nav.open { display: flex; }
}