/* =========================================================
   PG看台 · /assets/site.css
   共享外壳：坐标尺、框架式栏目轨道、页脚、基础组件
   ========================================================= */

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

:root {
  --ink: #12151A;
  --ink-soft: #2B3037;
  --helan: #6B7075;
  --stone: #C6C1B4;
  --paper: #F4F0E8;
  --paper-deep: #E6E0D3;
  --gold: #B98C2F;
  --gold-ink: #8A6414;
  --river: #B85C2E;
  --orange-ink: #9C4A1F;
  --cyan: #00D8C8;
  --cyan-ink: #067A72;

  --top-h: 56px;
  --rail-w: 72px;
  --content-max: 1240px;

  --font-display: "Noto Sans SC Condensed", "Source Han Sans SC", "PingFang SC", "Microsoft YaHei", system-ui, sans-serif;
  --font-heading: "Noto Sans SC Medium", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", system-ui, sans-serif;
  --font-body: "Noto Sans SC", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", system-ui, -apple-system, sans-serif;
  --font-mono: "JetBrains Mono", "IBM Plex Mono", ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;

  --dur-micro: 120ms;
  --dur: 220ms;
  --dur-band: 320ms;
  --ease: cubic-bezier(0.2, 0.6, 0.2, 1);
  --shadow: 0 1px 2px rgba(18, 21, 26, 0.06);
  --rule: 1px solid var(--stone);
  --read: 0;
}

html {
  -webkit-text-size-adjust: 100%;
  scroll-padding-top: calc(var(--top-h) + 18px);
  scroll-behavior: smooth;
}

body {
  margin: 0;
  padding: var(--top-h) var(--rail-w) 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.85;
  -webkit-font-smoothing: antialiased;
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 0;
  background-image:
    repeating-linear-gradient(0deg, rgba(18, 21, 26, 0.018) 0 1px, transparent 1px 3px);
  opacity: 0.7;
}

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

a { color: var(--cyan-ink); text-decoration: none; }
a:hover { text-decoration: underline; text-underline-offset: 3px; }

button { font: inherit; color: inherit; }

h1, h2, h3, h4, p, figure, blockquote { margin: 0; }

ul, ol { margin: 0; padding: 0; list-style: none; }

main { display: block; }

::selection { background: var(--cyan); color: var(--ink); }

:focus-visible { outline: 2px solid var(--cyan-ink); outline-offset: 2px; }

/* ---------- 排版基元 ---------- */

.display {
  font-family: var(--font-display);
  font-size: clamp(44px, 7vw, 96px);
  line-height: 0.98;
  letter-spacing: -0.03em;
  font-weight: 700;
}

h1, .h1 {
  font-family: var(--font-display);
  font-size: clamp(30px, 4vw, 52px);
  line-height: 1.15;
  letter-spacing: -0.02em;
  font-weight: 700;
}

h2, .h2 {
  font-family: var(--font-heading);
  font-size: clamp(22px, 2.4vw, 32px);
  line-height: 1.3;
  letter-spacing: -0.01em;
  font-weight: 600;
}

h3, .h3 {
  font-family: var(--font-heading);
  font-size: 18px;
  line-height: 1.5;
  font-weight: 600;
}

.prose { max-width: 34em; }
.prose p + p { margin-top: 1.1em; }
.prose h2 { margin: 2.2em 0 0.8em; }
.prose h3 { margin: 1.8em 0 0.6em; }
.prose ul, .prose ol { margin: 1em 0; padding-left: 1.35em; max-width: 34em; }
.prose ul { list-style: disc; }
.prose ol { list-style: decimal; }
.prose li { margin-bottom: 0.4em; }
.prose strong { font-weight: 600; }

.lede {
  font-size: clamp(17px, 1.6vw, 20px);
  line-height: 1.75;
  color: var(--ink-soft);
  max-width: 34em;
}

.note {
  font-family: var(--font-mono);
  font-size: 13px;
  line-height: 1.7;
  letter-spacing: 0.02em;
  color: var(--helan);
}

.sr-only {
  position: absolute;
  width: 1px; height: 1px;
  padding: 0; margin: -1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
  border: 0;
}

/* ---------- 版心与栅格 ---------- */

.wrap {
  width: 100%;
  max-width: var(--content-max);
  margin-inline: auto;
  padding-inline: clamp(20px, 4vw, 56px);
}

.section { padding-block: clamp(64px, 9vw, 140px); }
.section--tight { padding-block: clamp(40px, 5vw, 72px); }

.grid {
  display: grid;
  grid-template-columns: repeat(12, minmax(0, 1fr));
  gap: clamp(16px, 2.4vw, 32px);
}

.span-3 { grid-column: span 3; }
.span-4 { grid-column: span 4; }
.span-5 { grid-column: span 5; }
.span-6 { grid-column: span 6; }
.span-7 { grid-column: span 7; }
.span-8 { grid-column: span 8; }
.span-9 { grid-column: span 9; }
.span-12 { grid-column: span 12; }
.offset-1 { grid-column-start: 2; }
.offset-2 { grid-column-start: 3; }

/* ---------- 编号与刻度轨道 ---------- */

.sec-num {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.14em;
  color: var(--gold-ink);
  margin-bottom: 14px;
}
.sec-num--cyan { color: var(--cyan-ink); }

.track {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.12em;
  color: var(--helan);
}
.track__num {
  display: block;
  color: var(--gold-ink);
  margin-bottom: 6px;
}

/* ---------- 面包屑 ---------- */

.crumbs {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 26px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--helan);
}
.crumbs li { display: flex; align-items: center; gap: 8px; }
.crumbs li::after { content: "/"; color: var(--stone); }
.crumbs li:last-child::after { content: ""; }
.crumbs a { color: var(--helan); }
.crumbs a:hover { color: var(--cyan-ink); }
.crumbs [aria-current="page"] { color: var(--ink); }

/* =========================================================
   头部：顶部坐标尺 + 框架式栏目轨道
   ========================================================= */

.site-head { position: relative; z-index: 90; }

.skip {
  position: fixed;
  top: 8px;
  left: 8px;
  z-index: 200;
  transform: translateY(-180%);
  background: var(--ink);
  color: var(--paper);
  border: 1px solid var(--cyan);
  border-radius: 2px;
  padding: 10px 16px;
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.08em;
  transition: transform var(--dur-micro) var(--ease);
}
.skip:focus { transform: translateY(0); color: var(--paper); text-decoration: none; }

.frame-top {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--top-h);
  z-index: 95;
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 0 14px;
  background: var(--paper);
  border-bottom: var(--rule);
}

.tick {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 6px;
  pointer-events: none;
  opacity: 0.62;
  background-image: repeating-linear-gradient(90deg, var(--helan) 0 1px, transparent 1px 14px);
  transform-origin: left center;
  animation: tick-draw var(--dur-band) var(--ease) both;
}
.tick::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 2px;
  background: var(--cyan-ink);
  transform: scaleX(var(--read));
  transform-origin: left center;
  transition: transform var(--dur-micro) linear;
}
@keyframes tick-draw {
  from { transform: scaleX(0); }
  to { transform: scaleX(1); }
}

body[data-depth="1"] .tick { background-image: repeating-linear-gradient(90deg, var(--helan) 0 1px, transparent 1px 24px); }
body[data-depth="2"] .tick { background-image: repeating-linear-gradient(90deg, var(--helan) 0 1px, transparent 1px 14px); }
body[data-depth="3"] .tick { background-image: repeating-linear-gradient(90deg, var(--helan) 0 1px, transparent 1px 8px); }

.brand { display: flex; align-items: center; gap: 12px; min-width: 0; }

.brand__link { display: flex; align-items: center; gap: 10px; color: var(--ink); }
.brand__link:hover { color: var(--ink); text-decoration: none; }

.brand__mark {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  line-height: 1;
  padding: 5px 6px 4px;
  background: var(--ink);
  color: var(--paper);
  border: 1px solid var(--ink);
  border-radius: 2px;
}

.brand__name {
  font-family: var(--font-display);
  font-size: 20px;
  font-weight: 700;
  letter-spacing: -0.02em;
  line-height: 1;
  white-space: nowrap;
}

.brand__tag {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.18em;
  color: var(--helan);
  white-space: nowrap;
}

.head-meta { margin-left: auto; display: flex; align-items: center; gap: 14px; }

.head-coord {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.12em;
  color: var(--helan);
  white-space: nowrap;
}

.head-cta {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  padding: 8px 13px;
  background: var(--ink);
  color: var(--paper);
  border: 1px solid var(--ink);
  border-radius: 2px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  white-space: nowrap;
  transition: background var(--dur-micro) var(--ease), border-color var(--dur-micro) var(--ease);
}
.head-cta::after { content: "→"; }
.head-cta:hover {
  background: var(--cyan-ink);
  border-color: var(--cyan-ink);
  color: var(--paper);
  text-decoration: none;
}

.nav-toggle {
  display: none;
  align-items: center;
  gap: 9px;
  padding: 8px 12px;
  background: transparent;
  color: var(--ink);
  border: 1px solid var(--stone);
  border-radius: 2px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  cursor: pointer;
  transition: border-color var(--dur-micro) var(--ease), color var(--dur-micro) var(--ease);
}
.nav-toggle:hover { border-color: var(--ink); }

.nav-toggle__bars { position: relative; display: block; width: 16px; height: 10px; }
.nav-toggle__bars i {
  position: absolute;
  left: 0;
  right: 0;
  height: 1px;
  background: currentColor;
  transition: transform var(--dur) var(--ease);
}
.nav-toggle__bars i:nth-child(1) { top: 0; }
.nav-toggle__bars i:nth-child(2) { bottom: 0; }
.nav-toggle[aria-expanded="true"] .nav-toggle__bars i:nth-child(1) { transform: translateY(4.5px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] .nav-toggle__bars i:nth-child(2) { transform: translateY(-4.5px) rotate(-45deg); }

.nav-frame { position: fixed; inset: 0; z-index: 80; pointer-events: none; }

.rail {
  position: fixed;
  top: var(--top-h);
  bottom: 0;
  width: var(--rail-w);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 30px;
  background: var(--paper);
  pointer-events: auto;
}
.rail--l { left: 0; border-right: var(--rule); }
.rail--r { right: 0; border-left: var(--rule); }

.rail__item { display: block; }

.rail__link {
  position: relative;
  display: block;
  padding: 16px 0;
  writing-mode: vertical-rl;
  text-orientation: mixed;
  font-family: var(--font-heading);
  font-size: 14px;
  letter-spacing: 0.2em;
  line-height: 1;
  color: var(--ink-soft);
  transition: color var(--dur) var(--ease), letter-spacing var(--dur) var(--ease);
}
.rail__link::before {
  content: "";
  position: absolute;
  top: 2px;
  left: 50%;
  width: 6px;
  height: 6px;
  margin-left: -3px;
  border-radius: 50%;
  background: var(--stone);
  transition: background var(--dur) var(--ease), box-shadow var(--dur) var(--ease);
}
.rail__link:hover { color: var(--ink); text-decoration: none; letter-spacing: 0.26em; }
.rail__link:hover::before { background: var(--gold); }
.rail__link[aria-current="page"] { color: var(--ink); font-weight: 600; }
.rail__link[aria-current="page"]::before {
  background: var(--cyan-ink);
  box-shadow: 0 0 0 3px rgba(0, 216, 200, 0.32);
}

/* =========================================================
   页脚
   ========================================================= */

.site-foot {
  position: relative;
  z-index: 1;
  margin-top: clamp(64px, 8vw, 120px);
  background: var(--ink);
  color: var(--paper);
  border-top: 1px solid var(--ink-soft);
  padding-top: clamp(48px, 6vw, 72px);
}

.foot-grid {
  max-width: var(--content-max);
  margin-inline: auto;
  padding-inline: clamp(20px, 4vw, 56px);
  display: grid;
  grid-template-columns: 1.4fr 1fr 1fr 1fr 1.5fr;
  gap: 36px 28px;
}

.foot-brand__link {
  display: inline-block;
  font-family: var(--font-display);
  font-size: 22px;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--paper);
}
.foot-brand__link:hover { color: var(--cyan); text-decoration: none; }

.foot-brand__tag {
  margin-top: 10px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.18em;
  color: var(--helan);
}

.foot-brand__meta {
  margin-top: 20px;
  font-family: var(--font-mono);
  font-size: 12px;
  line-height: 1.9;
  letter-spacing: 0.06em;
  color: var(--helan);
}

.foot-col__title {
  margin: 0 0 14px;
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.18em;
  color: var(--cyan);
}

.foot-list li { margin-bottom: 10px; }
.foot-list a {
  color: rgba(244, 240, 232, 0.82);
  font-size: 14px;
  border-bottom: 1px solid transparent;
  transition: color var(--dur-micro) var(--ease), border-color var(--dur-micro) var(--ease);
}
.foot-list a:hover {
  color: var(--cyan);
  border-bottom-color: var(--cyan);
  text-decoration: none;
}

.foot-contact__item {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 8px;
  margin-bottom: 12px;
  font-size: 14px;
  line-height: 1.7;
}

.foot-contact__label {
  flex: 0 0 40px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.14em;
  color: var(--helan);
}

.foot-contact__value {
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.02em;
  color: rgba(244, 240, 232, 0.86);
  word-break: break-all;
}

.foot-contact__note {
  margin-top: 14px;
  font-size: 13px;
  line-height: 1.75;
  color: var(--helan);
  max-width: 30em;
}

.copy-btn {
  padding: 3px 8px;
  background: transparent;
  color: var(--cyan);
  border: 1px solid rgba(0, 216, 200, 0.45);
  border-radius: 2px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.1em;
  cursor: pointer;
  transition: background var(--dur-micro) var(--ease), color var(--dur-micro) var(--ease);
}
.copy-btn:hover { background: rgba(0, 216, 200, 0.14); }
.copy-btn:focus-visible { outline-color: var(--cyan); }

.foot-legal {
  max-width: var(--content-max);
  margin: 56px auto 0;
  padding: 22px clamp(20px, 4vw, 56px) 30px;
  border-top: 1px solid rgba(198, 193, 180, 0.18);
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 10px 24px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--helan);
}
.foot-legal__line { margin: 0; }

/* =========================================================
   基础组件
   ========================================================= */

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 11px 18px;
  background: var(--ink);
  color: var(--paper);
  border: 1px solid var(--ink);
  border-radius: 2px;
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.06em;
  transition: background var(--dur-micro) var(--ease), border-color var(--dur-micro) var(--ease), color var(--dur-micro) var(--ease);
}
.btn:hover { background: var(--cyan-ink); border-color: var(--cyan-ink); color: var(--paper); text-decoration: none; }

.btn--ghost { background: transparent; color: var(--ink); }
.btn--ghost:hover { background: var(--paper-deep); border-color: var(--ink); color: var(--ink); }

.btn--gold { background: var(--gold-ink); border-color: var(--gold-ink); }
.btn--gold:hover { background: var(--ink); border-color: var(--ink); }

.badge {
  display: inline-block;
  padding: 3px 8px;
  border: 1px solid currentColor;
  border-radius: 2px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.12em;
  color: var(--orange-ink);
}
.badge--cyan { color: var(--cyan-ink); }
.badge--gold { color: var(--gold-ink); }

.card {
  padding: clamp(20px, 2.4vw, 28px);
  background: rgba(255, 255, 255, 0.42);
  border: var(--rule);
  border-radius: 2px;
  box-shadow: var(--shadow);
}
.card__title {
  margin-bottom: 8px;
  font-family: var(--font-heading);
  font-size: 18px;
  font-weight: 600;
}
.card--ink {
  background: var(--ink-soft);
  border-color: var(--ink-soft);
  color: var(--paper);
}
.card--ink .card__title { color: var(--paper); }
.card--ink a { color: var(--cyan); }

.table {
  width: 100%;
  border-collapse: collapse;
  font-size: 15px;
  line-height: 1.6;
}
.table th,
.table td {
  padding: 10px 12px;
  border: var(--rule);
  text-align: left;
  vertical-align: top;
}
.table th {
  background: var(--paper-deep);
  font-family: var(--font-heading);
  font-weight: 600;
}
.table tbody tr:nth-child(even) { background: rgba(230, 224, 211, 0.45); }
.table .num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.02em;
}

.band {
  padding-block: clamp(28px, 3.6vw, 48px);
  background: var(--paper-deep);
  border-block: var(--rule);
}
.band--ink {
  background: var(--ink);
  color: var(--paper);
  border-color: var(--ink-soft);
}

.band__inner {
  display: flex;
  align-items: center;
  gap: clamp(24px, 4vw, 64px);
  overflow-x: auto;
  transition: transform var(--dur-band) var(--ease);
}
.band.is-in .band__inner { animation: band-nudge var(--dur-band) var(--ease) 1; }

.band__item {
  flex: 0 0 auto;
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.1em;
  white-space: nowrap;
}
.band__item--key { color: var(--gold-ink); }
.band--ink .band__item--key { color: var(--gold); }
.band--ink a { color: var(--cyan); }

@keyframes band-nudge {
  0% { transform: translateX(0); }
  45% { transform: translateX(8px); }
  100% { transform: translateX(0); }
}

.ridge {
  height: clamp(56px, 8vw, 110px);
  background: var(--ink);
  clip-path: polygon(0 100%, 0 74%, 5% 58%, 11% 68%, 18% 42%, 24% 60%, 31% 32%, 38% 54%, 45% 26%, 52% 52%, 59% 38%, 66% 62%, 73% 46%, 80% 66%, 87% 52%, 94% 70%, 100% 60%, 100% 100%);
}
.ridge--gold { background: var(--gold); }
.ridge--paper { background: var(--paper-deep); }

.media {
  position: relative;
  display: block;
  overflow: hidden;
  background: var(--paper-deep);
  border: var(--rule);
  border-radius: 2px;
}
.media > img,
.media > svg,
.media > picture { display: block; width: 100%; height: 100%; object-fit: cover; }

.media--band { aspect-ratio: 21 / 6; }
.media--ridge { aspect-ratio: 16 / 7; }
.media--wide { aspect-ratio: 16 / 9; }
.media--square { aspect-ratio: 1 / 1; }

.media--grid::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background-image:
    repeating-linear-gradient(90deg, rgba(244, 240, 232, 0.2) 0 1px, transparent 1px 10%),
    repeating-linear-gradient(0deg, rgba(244, 240, 232, 0.2) 0 1px, transparent 1px 22%);
}

.media__cap {
  position: absolute;
  left: 0;
  bottom: 0;
  max-width: 100%;
  padding: 6px 10px;
  background: rgba(18, 21, 26, 0.86);
  color: var(--paper);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  line-height: 1.5;
}

.toc {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.1em;
  line-height: 1.9;
}
.toc__link {
  position: relative;
  display: block;
  padding: 6px 0 6px 16px;
  color: var(--helan);
}
.toc__link::before {
  content: "";
  position: absolute;
  left: 0;
  top: 1.05em;
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: var(--stone);
  transition: background var(--dur) var(--ease), box-shadow var(--dur) var(--ease);
}
.toc__link:hover { color: var(--ink); text-decoration: none; }
.toc__link[aria-current="true"] { color: var(--ink); font-weight: 600; }
.toc__link[aria-current="true"]::before {
  background: var(--cyan-ink);
  box-shadow: 0 0 0 3px rgba(0, 216, 200, 0.28);
}

.to-top {
  position: fixed;
  right: calc(var(--rail-w) + 16px);
  bottom: calc(20px + env(safe-area-inset-bottom, 0px));
  z-index: 78;
  width: 44px;
  height: 44px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background: var(--paper);
  color: var(--ink);
  border: var(--rule);
  border-radius: 2px;
  box-shadow: var(--shadow);
  cursor: pointer;
  opacity: 0;
  transform: translateY(10px);
  pointer-events: none;
  transition: opacity var(--dur) var(--ease), transform var(--dur) var(--ease), background var(--dur-micro) var(--ease), color var(--dur-micro) var(--ease);
}
.to-top.is-on { opacity: 1; transform: none; pointer-events: auto; }
.to-top:hover { background: var(--ink); color: var(--cyan); }
.to-top__glyph { font-family: var(--font-mono); font-size: 16px; line-height: 1; }

/* =========================================================
   响应式
   ========================================================= */

@media (max-width: 1200px) {
  .foot-grid { grid-template-columns: 1.4fr 1fr 1fr 1fr 1.5fr; gap: 32px 22px; }
}

@media (max-width: 1023px) {
  :root { --rail-w: 0px; }

  .head-coord { display: none; }
  .nav-toggle { display: inline-flex; }

  .nav-frame {
    position: fixed;
    left: 0;
    right: 0;
    bottom: 0;
    top: auto;
    z-index: 100;
    max-height: 82vh;
    overflow-y: auto;
    padding: 18px 20px calc(26px + env(safe-area-inset-bottom, 0px));
    background: var(--ink);
    color: var(--paper);
    border-top: 2px solid var(--cyan);
    box-shadow: 0 -1px 2px rgba(18, 21, 26, 0.12);
    transform: translateY(102%);
    visibility: hidden;
    pointer-events: auto;
    transition: transform var(--dur) var(--ease), visibility 0s linear var(--dur);
  }
  .nav-frame[data-open] {
    transform: translateY(0);
    visibility: visible;
    transition: transform var(--dur) var(--ease), visibility 0s linear 0s;
  }

  .rail {
    position: static;
    width: auto;
    background: transparent;
    border: 0;
    gap: 0;
    align-items: stretch;
    justify-content: flex-start;
  }
  .rail--l, .rail--r { left: auto; right: auto; top: auto; bottom: auto; }
  .rail__item { border-bottom: 1px solid rgba(198, 193, 180, 0.18); }

  .rail__link {
    display: flex;
    align-items: center;
    writing-mode: horizontal-tb;
    padding: 14px 4px;
    font-size: 16px;
    letter-spacing: 0.06em;
    color: rgba(244, 240, 232, 0.9);
  }
  .rail__link::before {
    position: static;
    margin: 0 12px 0 0;
    flex: 0 0 auto;
    background: rgba(198, 193, 180, 0.55);
  }
  .rail__link:hover { color: var(--paper); letter-spacing: 0.06em; }
  .rail__link:hover::before { background: var(--gold); }
  .rail__link[aria-current="page"] { color: var(--cyan); }
  .rail__link[aria-current="page"]::before {
    background: var(--cyan);
    box-shadow: 0 0 0 3px rgba(0, 216, 200, 0.22);
  }

  .foot-grid { grid-template-columns: 1fr 1fr; gap: 32px 24px; }
  .foot-brand { grid-column: 1 / -1; }
  .foot-contact { grid-column: 1 / -1; }
}

@media (max-width: 900px) {
  .span-3, .span-4, .span-5, .span-6,
  .span-7, .span-8, .span-9, .span-12,
  .offset-1, .offset-2 { grid-column: 1 / -1; }

  .band__inner { gap: 24px; }
}

@media (max-width: 620px) {
  .frame-top { gap: 10px; padding: 0 10px; }
  .brand__tag { display: none; }
  .brand__name { font-size: 18px; }
  .head-cta { padding: 7px 10px; font-size: 11px; }
  .nav-toggle__label { display: none; }

  .foot-grid { grid-template-columns: 1fr; }
  .foot-legal { flex-direction: column; }

  .to-top { width: 40px; height: 40px; }
}

@media (max-width: 420px) {
  .head-cta { display: none; }
}

/* =========================================================
   动效降级
   ========================================================= */

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }

  *, *::before, *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
  }

  .tick { transform: none; animation: none; }
  .nav-frame { transition: none; }
  .to-top { transform: none; }
  .band__inner { transform: none !important; }
}