/* ============================================================
   9博平台 · /assets/site.css
   共享外壳：命令栏头部、页脚、通用组件与栅格
   ============================================================ */

/* ---------- 1. Reset ---------- */
*,
*::before,
*::after { box-sizing: border-box; }

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background-color: var(--ink);
  background-image:
    radial-gradient(1100px 520px at 82% -8%, rgba(63, 224, 208, 0.10), transparent 60%),
    radial-gradient(900px 480px at 4% 12%, rgba(255, 178, 92, 0.07), transparent 62%),
    repeating-linear-gradient(90deg, rgba(30, 59, 84, 0.30) 0 1px, transparent 1px 104px);
  color: var(--paper);
  font-family: var(--font-body);
  font-size: var(--fs-body);
  line-height: 1.85;
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
}

img, svg, video { display: block; max-width: 100%; }
ul, ol { margin: 0; padding: 0; list-style: none; }
button, input, select, textarea { font: inherit; color: inherit; }
a { color: inherit; text-decoration: none; }
table { border-collapse: collapse; width: 100%; }
hr { border: 0; }

:focus-visible {
  outline: 2px solid var(--cyan);
  outline-offset: 3px;
  border-radius: 4px;
}

/* ---------- 2. Tokens ---------- */
:root {
  --ink: #0A1A2B;
  --ink-deep: #071320;
  --card: #12293D;
  --line: #1E3B54;
  --cyan: #3FE0D0;
  --amber: #FFB25C;
  --paper: #F6F1E6;
  --paper-2: #E6DECB;
  --fog: #9FB0C0;
  --ok: #57D9A3;
  --err: #FF7A6B;

  --font-head: "Noto Sans SC Condensed", "Source Han Sans SC", "PingFang SC", "Microsoft YaHei", system-ui, sans-serif;
  --font-body: system-ui, -apple-system, "PingFang SC", "Microsoft YaHei", "Noto Sans SC", sans-serif;
  --font-mono: ui-monospace, "JetBrains Mono", Menlo, Consolas, "Courier New", monospace;

  --fs-12: 12px;
  --fs-14: 14px;
  --fs-16: 16px;
  --fs-20: 20px;
  --fs-24: 24px;
  --fs-34: 34px;
  --fs-48: 48px;
  --fs-64: 64px;
  --fs-body: clamp(16px, 1.05vw + 12px, 17.5px);

  --radius-lg: 28px;
  --radius-md: 18px;
  --radius-sm: 10px;
  --pill: 999px;
  --gutter: clamp(16px, 4vw, 40px);
  --bar-h: 56px;
  --bar-h-collapsed: 40px;
  --ease: cubic-bezier(0.22, 0.61, 0.36, 1);
}

/* ---------- 3. 中文排版 ---------- */
h1, h2, h3, h4 {
  font-family: var(--font-head);
  font-weight: 800;
  letter-spacing: -0.02em;
  line-height: 1.16;
  margin: 0 0 0.5em;
  font-stretch: condensed;
}

h1 { font-size: clamp(34px, 5.4vw, 56px); font-weight: 900; }
h2 { font-size: clamp(26px, 3.6vw, 34px); }
h3 { font-size: clamp(19px, 2vw, 24px); }
h4 { font-size: var(--fs-20); }

p { margin: 0 0 1.2em; }
p:last-child { margin-bottom: 0; }

strong { color: var(--amber); font-weight: 700; }

.mono {
  font-family: var(--font-mono);
  font-size: 0.86em;
  letter-spacing: 0.04em;
  font-variant-numeric: tabular-nums;
}

.eyebrow {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: var(--fs-12);
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--cyan);
  margin-bottom: 14px;
}

.big-num {
  display: block;
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: clamp(56px, 12vw, 140px);
  line-height: 0.9;
  letter-spacing: -0.04em;
  color: var(--cyan);
}

.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;
}

.skip-link {
  position: absolute;
  left: 12px;
  top: -60px;
  z-index: 200;
  padding: 10px 18px;
  border-radius: var(--pill);
  background: var(--cyan);
  color: var(--ink-deep);
  font-weight: 700;
  font-size: var(--fs-14);
  transition: top 0.18s var(--ease);
}
.skip-link:focus { top: 12px; }

/* ---------- 4. 容器与栅格 ---------- */
.container {
  width: min(1240px, 100% - (var(--gutter) * 2));
  margin-inline: auto;
}

.section { padding-block: clamp(48px, 7vw, 104px); }
.section--tight { padding-block: clamp(28px, 4vw, 56px); }
.section--deep { background: var(--ink-deep); }
.section--paper {
  background: var(--paper);
  color: var(--ink);
  background-image: repeating-linear-gradient(0deg, rgba(10, 26, 43, 0.045) 0 1px, transparent 1px 32px);
}
.section--paper .eyebrow { color: #4C6172; }
.section--paper .big-num { color: #0A1A2B; opacity: 0.9; }

.grid { display: grid; gap: clamp(16px, 2.2vw, 28px); }
.grid--12 { grid-template-columns: repeat(12, minmax(0, 1fr)); }
.grid--12 > * { grid-column: span 12; }

@media (min-width: 760px) {
  .col-3 { grid-column: span 3; }
  .col-4 { grid-column: span 4; }
  .col-5 { grid-column: span 5; }
  .col-6 { grid-column: span 6; }
  .col-7 { grid-column: span 7; }
  .col-8 { grid-column: span 8; }
  .col-9 { grid-column: span 9; }
  .col-12 { grid-column: span 12; }
}

.stack-sm { display: grid; gap: 12px; }
.stack-md { display: grid; gap: 20px; }
.rule { height: 1px; background: var(--line); border: 0; margin: 0; }

/* ---------- 5. 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 22px;
  border-radius: var(--pill);
  border: 1px solid transparent;
  font-size: 15px;
  font-weight: 700;
  letter-spacing: 0.01em;
  cursor: pointer;
  background: transparent;
  transition: transform 0.18s var(--ease), background-color 0.18s var(--ease),
    border-color 0.18s var(--ease), color 0.18s var(--ease);
}
.btn:hover { transform: translateY(-2px); }
.btn:active { transform: translateY(0); }

.btn--primary { background: var(--cyan); color: var(--ink-deep); }
.btn--primary:hover { background: #5CEADD; }

.btn--amber { background: var(--amber); color: var(--ink-deep); }
.btn--amber:hover { background: #FFC684; }

.btn--ghost { border-color: var(--line); color: var(--paper); }
.btn--ghost:hover { border-color: var(--cyan); color: var(--cyan); }

.btn--sm { padding: 8px 16px; font-size: 13.5px; }
.btn--block { width: 100%; }

/* ---------- 6. 状态点 ---------- */
.status-dot {
  display: inline-block;
  width: 8px; height: 8px;
  border-radius: 50%;
  background: var(--cyan);
  box-shadow: 0 0 0 4px rgba(63, 224, 208, 0.16);
}
.status-dot--ok { background: var(--ok); box-shadow: 0 0 0 4px rgba(87, 217, 163, 0.16); }
.status-dot--warn { background: var(--amber); box-shadow: 0 0 0 4px rgba(255, 178, 92, 0.16); }
.status-dot--err { background: var(--err); box-shadow: 0 0 0 4px rgba(255, 122, 107, 0.16); }
.status-dot--pulse { animation: dot-breath 2.6s var(--ease) infinite; }

@keyframes dot-breath {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.42; }
}

/* ---------- 7. 命令栏头部 ---------- */
.cmd-bar {
  position: sticky;
  top: 0;
  z-index: 80;
  background: rgba(7, 19, 32, 0.94);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
}

.scroll-progress {
  position: absolute;
  left: 0; right: 0; bottom: -1px;
  height: 2px;
  overflow: hidden;
  pointer-events: none;
}
.scroll-progress__bar {
  display: block;
  height: 100%;
  width: 100%;
  transform: scaleX(0);
  transform-origin: 0 50%;
  background: linear-gradient(90deg, var(--cyan), var(--amber));
  transition: transform 0.12s linear;
}

.cmd-bar__inner {
  position: relative;
  display: flex;
  align-items: center;
  gap: clamp(10px, 1.6vw, 24px);
  width: min(1440px, 100% - (var(--gutter) * 2));
  margin-inline: auto;
  height: var(--bar-h);
  transition: height 0.24s var(--ease);
}
.cmd-bar[data-collapsed="true"] .cmd-bar__inner { height: var(--bar-h-collapsed); }

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  flex: 0 0 auto;
}
.brand__dot {
  width: 9px; height: 9px;
  border-radius: 50%;
  background: var(--ok);
  box-shadow: 0 0 0 4px rgba(87, 217, 163, 0.16);
  animation: dot-breath 3s var(--ease) infinite;
}
.brand__text { display: flex; flex-direction: column; gap: 3px; line-height: 1; }
.brand__mark {
  font-family: var(--font-head);
  font-weight: 900;
  font-size: 17px;
  letter-spacing: -0.01em;
  color: var(--paper);
}
.brand__meta { font-size: 10.5px; color: var(--fog); letter-spacing: 0.14em; }
.cmd-bar[data-collapsed="true"] .brand__meta { display: none; }

/* 导航 */
.nav { flex: 1 1 auto; min-width: 0; }
.nav__list {
  display: flex;
  align-items: center;
  gap: clamp(4px, 1vw, 16px);
}
.nav__link {
  position: relative;
  display: inline-flex;
  align-items: center;
  gap: 7px;
  padding: 8px 10px;
  border-radius: var(--pill);
  font-size: 14.5px;
  font-weight: 600;
  color: var(--paper);
  white-space: nowrap;
  transition: background-color 0.18s var(--ease), color 0.18s var(--ease);
}
.nav__idx { font-size: 11px; color: var(--fog); }
.nav__link:hover { background: rgba(63, 224, 208, 0.09); color: var(--cyan); }
.nav__link:hover .nav__idx { color: var(--amber); }

.nav__link[aria-current="page"] { color: var(--cyan); }
.nav__link[aria-current="page"] .nav__idx { color: var(--amber); }
.nav__link[aria-current="page"]::after {
  content: "";
  position: absolute;
  left: 10px; right: 10px; bottom: 1px;
  height: 2px;
  border-radius: 2px;
  background: var(--amber);
}

.nav__item.is-filtered { display: none; }

/* 当前栏目名（收起态显示） */
.cmd-bar__current {
  display: none;
  align-items: center;
  padding: 4px 12px;
  border: 1px solid var(--line);
  border-radius: var(--pill);
  color: var(--amber);
  font-size: 12px;
  letter-spacing: 0.12em;
}
.cmd-bar__current:empty { display: none !important; }

.cmd-bar__tools {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-left: auto;
  flex: 0 0 auto;
}

/* 搜索 */
.search { position: relative; }
.search__input {
  width: clamp(116px, 15vw, 200px);
  padding: 8px 14px;
  border-radius: var(--pill);
  border: 1px solid var(--line);
  background: rgba(10, 26, 43, 0.86);
  color: var(--paper);
  font-size: 13.5px;
  transition: border-color 0.18s var(--ease), box-shadow 0.18s var(--ease);
}
.search__input::placeholder { color: var(--fog); }
.search__input:focus {
  outline: none;
  border-color: var(--cyan);
  box-shadow: 0 0 0 3px rgba(63, 224, 208, 0.16);
}
.search__results {
  position: absolute;
  top: calc(100% + 10px);
  right: 0;
  width: min(320px, 84vw);
  padding: 8px;
  z-index: 90;
  background: var(--ink-deep);
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  box-shadow: 0 20px 44px rgba(0, 0, 0, 0.5);
}
.search__results[hidden] { display: none; }
.search__result {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 9px 12px;
  border-radius: var(--radius-sm);
  font-size: 14px;
  color: var(--paper);
}
.search__result .mono { color: var(--fog); font-size: 11.5px; }
.search__result:hover,
.search__result:focus-visible { background: rgba(63, 224, 208, 0.1); color: var(--cyan); }
.search__hint {
  padding: 9px 12px;
  font-family: var(--font-mono);
  font-size: 12px;
  line-height: 1.6;
  color: var(--fog);
}

/* 移动导航按钮 */
.nav-toggle {
  display: none;
  align-items: center;
  gap: 9px;
  padding: 9px 14px;
  border-radius: var(--pill);
  border: 1px solid var(--line);
  background: transparent;
  color: var(--paper);
  cursor: pointer;
  font-size: 13.5px;
  font-weight: 700;
}
.nav-toggle:hover { border-color: var(--cyan); color: var(--cyan); }
.nav-toggle__bars { display: inline-flex; flex-direction: column; gap: 4px; width: 18px; }
.nav-toggle__bars i { display: block; height: 2px; border-radius: 2px; background: currentColor; }

/* 收起态返回顶部 */
.cmd-bar__top {
  display: none;
  align-items: center;
  gap: 6px;
  margin-left: 4px;
  padding: 6px 14px;
  border-radius: var(--pill);
  border: 1px solid var(--line);
  background: transparent;
  color: var(--fog);
  font-size: 12px;
  letter-spacing: 0.06em;
  cursor: pointer;
  flex: 0 0 auto;
}
.cmd-bar__top:hover { color: var(--cyan); border-color: var(--cyan); }
.cmd-bar[data-collapsed="true"] .cmd-bar__top { display: inline-flex; }

.cmd-bar[data-collapsed="true"] .nav,
.cmd-bar[data-collapsed="true"] .search,
.cmd-bar[data-collapsed="true"] .cmd-bar__contact,
.cmd-bar[data-collapsed="true"] .cmd-bar__cta,
.cmd-bar[data-collapsed="true"] .nav-toggle { display: none; }

.cmd-bar[data-collapsed="true"] .cmd-bar__current { display: inline-flex; }

/* ---------- 8. 通用内容组件 ---------- */
.panel--card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  padding: clamp(20px, 2.6vw, 32px);
}
.panel--paper {
  background: var(--paper);
  color: var(--ink);
  border: 1px solid var(--paper-2);
  border-radius: var(--radius-lg);
  padding: clamp(20px, 3vw, 40px);
}
.panel--paper .mono { color: #55697C; }

.tag {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 5px 12px;
  border-radius: var(--pill);
  border: 1px solid var(--line);
  background: rgba(18, 41, 61, 0.7);
  color: var(--fog);
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.chip {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 7px 15px;
  border-radius: var(--pill);
  border: 1px solid var(--line);
  background: rgba(63, 224, 208, 0.06);
  color: var(--paper);
  font-family: var(--font-mono);
  font-size: 12.5px;
  letter-spacing: 0.04em;
  cursor: pointer;
  transition: background-color 0.18s var(--ease), color 0.18s var(--ease),
    border-color 0.18s var(--ease);
}
.chip:hover { border-color: var(--cyan); color: var(--cyan); }
.chip.is-active,
.chip[aria-pressed="true"] {
  background: var(--cyan);
  border-color: var(--cyan);
  color: var(--ink-deep);
}

.label-band {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 4px 0 14px;
  overflow-x: auto;
  scroll-snap-type: x proximity;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: thin;
  scrollbar-color: var(--line) transparent;
}
.label-band > * { flex: 0 0 auto; scroll-snap-align: start; }
.label-band::-webkit-scrollbar { height: 6px; }
.label-band::-webkit-scrollbar-thumb { background: var(--line); border-radius: 3px; }

.index-block {
  display: flex;
  gap: 16px;
  padding: 20px;
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  transition: transform 0.2s var(--ease), border-color 0.2s var(--ease);
}
.index-block:hover { transform: translateY(-2px); border-color: var(--cyan); }
.index-block__num {
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.1em;
  color: var(--amber);
  flex: 0 0 auto;
}
.index-block__title { margin: 0 0 6px; font-size: 17px; font-weight: 700; }
.index-block__desc { margin: 0; font-size: 14.5px; line-height: 1.8; color: var(--fog); }

.step-list { display: grid; gap: 12px; }
.step {
  display: flex;
  gap: 14px;
  padding: 14px 16px;
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  background: rgba(18, 41, 61, 0.6);
}
.step__num {
  flex: 0 0 auto;
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.08em;
  color: var(--amber);
}
.step__text { margin: 0; font-size: 15.5px; line-height: 1.8; }

.fold {
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  background: var(--card);
  overflow: hidden;
}
.fold + .fold { margin-top: 12px; }
.fold__head {
  display: flex;
  align-items: center;
  gap: 14px;
  width: 100%;
  padding: 16px 20px;
  border: 0;
  background: transparent;
  color: var(--paper);
  font-size: 16px;
  font-weight: 700;
  text-align: left;
  cursor: pointer;
  transition: background-color 0.18s var(--ease);
}
.fold__head:hover { background: rgba(63, 224, 208, 0.07); }
.fold__chev {
  margin-left: auto;
  color: var(--cyan);
  font-family: var(--font-mono);
  transition: transform 0.2s var(--ease);
}
.fold[data-open] .fold__chev { transform: rotate(90deg); }
.fold__body {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.22s var(--ease);
}
.fold[data-open] .fold__body { max-height: 2000px; }
.fold__inner {
  padding: 0 20px 20px;
  color: var(--fog);
  font-size: 15px;
  line-height: 1.85;
}

.timeline { position: relative; padding-left: 26px; }
.timeline::before {
  content: "";
  position: absolute;
  left: 5px; top: 8px; bottom: 8px;
  width: 2px;
  background: linear-gradient(180deg, var(--cyan), rgba(63, 224, 208, 0));
}
.timeline__item { position: relative; padding-block: 12px; }
.timeline__item::before {
  content: "";
  position: absolute;
  left: -25px; top: 22px;
  width: 10px; height: 10px;
  border-radius: 50%;
  background: var(--amber);
  box-shadow: 0 0 0 4px rgba(255, 178, 92, 0.14);
}
.timeline__time {
  display: block;
  font-family: var(--font-mono);
  font-size: 12.5px;
  letter-spacing: 0.06em;
  color: var(--fog);
  margin-bottom: 4px;
}

.toc {
  position: sticky;
  top: calc(var(--bar-h) + 20px);
  align-self: start;
  width: min(200px, 100%);
  padding-left: 16px;
  border-left: 1px solid var(--line);
}
.toc__title {
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--fog);
  margin-bottom: 12px;
}
.toc__link {
  display: block;
  margin-left: -18px;
  padding: 6px 0 6px 16px;
  border-left: 2px solid transparent;
  font-size: 13.5px;
  color: var(--fog);
  transition: color 0.18s var(--ease), border-color 0.18s var(--ease);
}
.toc__link:hover { color: var(--paper); }
.toc__link[aria-current="true"] { color: var(--cyan); border-left-color: var(--cyan); }

.breadcrumbs {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px;
  padding-block: 18px;
  font-family: var(--font-mono);
  font-size: 12.5px;
  letter-spacing: 0.04em;
  color: var(--fog);
}
.breadcrumbs ol { display: flex; flex-wrap: wrap; align-items: center; gap: 10px; }
.breadcrumbs li + li::before { content: "/"; margin-right: 10px; color: var(--line); }
.breadcrumbs a:hover { color: var(--cyan); }
.breadcrumbs [aria-current="page"] { color: var(--paper); }

/* ---------- 9. 图片容器（页面阶段放置占位） ---------- */
.media-frame {
  position: relative;
  overflow: hidden;
  aspect-ratio: 16 / 9;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background:
    linear-gradient(150deg, rgba(18, 41, 61, 0.95), rgba(7, 19, 32, 0.95));
}
.media-frame img,
.media-frame svg,
.media-frame video {
  width: 100%;
  height: 100%;
  object-fit: cover;
}
.media-frame--wide { aspect-ratio: 21 / 9; }
.media-frame--tall { aspect-ratio: 3 / 4; }
.media-frame--square { aspect-ratio: 1 / 1; }
.media-frame__caption {
  margin: 10px 0 0;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.04em;
  color: var(--fog);
}
.section--paper .media-frame { border-color: var(--paper-2); }

/* ---------- 10. 页脚 ---------- */
.site-footer {
  position: relative;
  background: var(--ink-deep);
  border-top: 1px solid var(--line);
  padding-block: clamp(40px, 6vw, 72px) 28px;
  color: var(--paper);
}

.footer__grid {
  display: grid;
  gap: clamp(24px, 3vw, 40px);
  grid-template-columns: 1fr;
}
@media (min-width: 720px) {
  .footer__grid { grid-template-columns: 1.5fr 1fr 1fr 1fr; }
}

.footer__col { min-width: 0; }
.footer__col--brand { display: flex; flex-direction: column; align-items: flex-start; }
.brand--footer .brand__mark { font-size: 19px; }
.footer__about {
  margin: 16px 0 0;
  max-width: 34ch;
  font-size: 14.5px;
  line-height: 1.85;
  color: var(--fog);
}
.footer__legal {
  margin: 14px 0 0;
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--fog);
}

.footer__title {
  margin: 0 0 14px;
  font-family: var(--font-mono);
  font-size: 11.5px;
  font-weight: 600;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--fog);
}
.footer__list li + li { margin-top: 9px; }
.footer__link {
  display: inline-block;
  font-size: 14.5px;
  color: var(--paper);
  border-bottom: 1px solid transparent;
  transition: color 0.18s var(--ease), border-color 0.18s var(--ease);
}
.footer__link:hover { color: var(--cyan); border-bottom-color: var(--cyan); }

.footer__contact {
  display: grid;
  gap: 14px;
  margin-top: clamp(28px, 4vw, 44px);
  padding-top: 22px;
  border-top: 1px dashed var(--line);
}
@media (min-width: 720px) {
  .footer__contact { grid-template-columns: repeat(3, minmax(0, 1fr)); }
}
.footer__contact-item { margin: 0; }
.footer__contact-key {
  display: block;
  margin-bottom: 5px;
  font-size: 11.5px;
  letter-spacing: 0.14em;
  color: var(--fog);
}
.footer__contact-value { font-size: 14.5px; color: var(--paper); word-break: break-word; }

.footer__bottom {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 12px 24px;
  margin-top: 26px;
  padding-top: 18px;
  border-top: 1px solid var(--line);
  color: var(--fog);
  font-size: 12.5px;
}
.footer__note { margin: 0; max-width: 62ch; line-height: 1.7; }
.footer__copy { margin: 0; letter-spacing: 0.08em; }

/* 浮动返回顶部 */
.back-to-top {
  position: fixed;
  right: clamp(14px, 3vw, 32px);
  bottom: clamp(14px, 3vw, 32px);
  z-index: 70;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 11px 18px;
  border-radius: var(--pill);
  border: 1px solid var(--line);
  background: rgba(7, 19, 32, 0.94);
  color: var(--paper);
  font-size: 13.5px;
  font-weight: 700;
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transform: translateY(10px);
  transition: opacity 0.22s var(--ease), transform 0.22s var(--ease),
    border-color 0.2s var(--ease), color 0.2s var(--ease), visibility 0.22s;
}
.back-to-top[data-visible="true"] { opacity: 1; visibility: visible; transform: none; }
.back-to-top:hover { border-color: var(--cyan); color: var(--cyan); }
.back-to-top__arrow { font-size: 15px; color: var(--amber); }

/* ---------- 11. 显现动效 ---------- */
[data-reveal] {
  opacity: 0;
  transform: translateY(14px);
  transition: opacity 0.5s var(--ease), transform 0.5s var(--ease);
}
[data-reveal].is-visible { opacity: 1; transform: none; }

/* ---------- 12. 断点：平板与手机 ---------- */
@media (max-width: 1080px) {
  .cmd-bar__contact { display: none; }
}

@media (max-width: 860px) {
  .cmd-bar__inner { gap: 10px; }
  .nav-toggle { display: inline-flex; }

  .nav {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    max-height: 72vh;
    overflow-y: auto;
    padding: 10px 0 18px;
    background: var(--ink-deep);
    border-bottom: 1px solid var(--line);
    box-shadow: 0 24px 48px rgba(0, 0, 0, 0.45);
  }
  .nav[data-open] { display: block; }
  .nav__list { flex-direction: column; align-items: stretch; gap: 2px; }
  .nav__link {
    justify-content: flex-start;
    padding: 13px 14px;
    border-radius: var(--radius-sm);
    font-size: 16px;
  }
  .nav__link[aria-current="page"] {
    background: rgba(255, 178, 92, 0.1);
    color: var(--amber);
  }
  .nav__link[aria-current="page"]::after {
    left: 14px; right: auto;
    top: 50%; bottom: auto;
    width: 3px; height: 18px;
    transform: translateY(-50%);
  }
  .cmd-bar__top { display: none !important; }
  .cmd-bar__current { display: none !important; }
  .toc {
    position: static;
    width: 100%;
    border-left: 0;
    border-top: 1px solid var(--line);
    padding: 14px 0 0;
  }
  .toc__link { margin-left: 0; padding-left: 12px; }
}

@media (max-width: 560px) {
  .search__input { width: 104px; }
  .cmd-bar__cta { display: none; }
  .brand__meta { display: none; }
  .back-to-top__text { display: none; }
  .back-to-top { padding: 12px 15px; }
}

/* ---------- 13. 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;
    scroll-behavior: auto !important;
  }
  [data-reveal] { opacity: 1; transform: none; }
  .btn:hover,
  .index-block:hover { transform: none; }
}