/* ==========================================================================
   亿德主页 · /assets/site.css
   共享外壳：命令栏头部、页脚、通用按钮、栅格与基础组件
   ========================================================================== */

/* ---------- 1. 设计变量 ---------- */
:root {
  --ink-deep: #071429;
  --ink: #0A1E3C;
  --ink-soft: #142C4E;
  --cyan: #00E5FF;
  --orange: #FF6B35;
  --paper: #F6F1E7;
  --text: #E8F0FE;
  --muted: #8FA6C4;
  --ok: #2BD9A8;
  --warn: #FFB020;

  --line: rgba(232, 240, 254, 0.12);
  --line-strong: rgba(232, 240, 254, 0.24);

  --rail: 88px;
  --shell-max: 1180px;
  --radius: 20px;
  --radius-sm: 14px;
  --cut: 18px;
  --band: clamp(56px, 8vw, 104px);
  --lift: 0 20px 44px rgba(0, 0, 0, 0.38);

  --font-sans: "Inter", "Source Han Sans SC", "Noto Sans SC", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", system-ui, -apple-system, sans-serif;
  --font-mono: "JetBrains Mono", "SFMono-Regular", ui-monospace, "Cascadia Mono",
    "Roboto Mono", Consolas, monospace;
}

/* ---------- 2. Reset ---------- */
*,
*::before,
*::after { box-sizing: border-box; }

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

body {
  margin: 0;
  min-height: 100vh;
  background-color: var(--ink);
  color: var(--text);
  font-family: var(--font-sans);
  font-size: 16px;
  font-weight: 500;
  line-height: 1.75;
  letter-spacing: 0.01em;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

/* 舱体网格与光晕 */
body::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  background-image:
    linear-gradient(rgba(232, 240, 254, 0.032) 1px, transparent 1px),
    linear-gradient(90deg, rgba(232, 240, 254, 0.032) 1px, transparent 1px);
  background-size: 88px 88px;
  -webkit-mask-image: radial-gradient(125% 90% at 24% 0%, #000 0%, rgba(0, 0, 0, 0.35) 62%, transparent 100%);
  mask-image: radial-gradient(125% 90% at 24% 0%, #000 0%, rgba(0, 0, 0, 0.35) 62%, transparent 100%);
}

body::after {
  content: "";
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  background:
    radial-gradient(52% 38% at 84% 6%, rgba(0, 229, 255, 0.13), transparent 70%),
    radial-gradient(48% 34% at 6% 92%, rgba(255, 107, 53, 0.10), transparent 72%);
}

h1, h2, h3, h4, h5, h6 {
  margin: 0;
  color: var(--text);
  font-weight: 800;
  line-height: 1.18;
  letter-spacing: -0.012em;
}

p { margin: 0 0 1.1em; }
p:last-child { margin-bottom: 0; }

ul, ol { margin: 0 0 1.1em; padding-left: 1.25em; }
li { margin-bottom: 0.35em; }

a { color: var(--cyan); text-decoration: none; }
a:hover { text-decoration: underline; text-underline-offset: 4px; }

strong, b { color: #ffffff; font-weight: 700; }
small { font-size: 0.85em; }

code, kbd, samp, pre { font-family: var(--font-mono); font-size: 0.92em; }

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

button {
  font: inherit;
  color: inherit;
  background: none;
  border: 0;
  padding: 0;
  cursor: pointer;
}

hr { border: 0; border-top: 1px solid var(--line); margin: 2.2em 0; }

::selection { background: rgba(0, 229, 255, 0.3); color: #ffffff; }

:focus-visible {
  outline: 2px solid var(--cyan);
  outline-offset: 3px;
  border-radius: 6px;
}

[id] { scroll-margin-top: 84px; }

/* ---------- 3. 布局容器 ---------- */
.container {
  width: 100%;
  max-width: var(--shell-max);
  margin-inline: auto;
  padding-inline: clamp(18px, 4vw, 32px);
}

#main-content {
  position: relative;
  z-index: 1;
  min-height: 60vh;
}

.grid { display: grid; gap: 24px; }

.grid--7-5 { grid-template-columns: 7fr 5fr; }
.grid--5-7 { grid-template-columns: 5fr 7fr; }
.grid--halves { grid-template-columns: repeat(2, minmax(0, 1fr)); }

@media (max-width: 860px) {
  .grid--7-5,
  .grid--5-7,
  .grid--halves { grid-template-columns: minmax(0, 1fr); }
}

/* ---------- 4. 跳过链接 ---------- */
.skip-link {
  position: fixed;
  left: 14px;
  top: -80px;
  z-index: 300;
  padding: 11px 18px;
  background: var(--cyan);
  color: #04121f;
  font-size: 14px;
  font-weight: 700;
  border-radius: 0 0 12px 12px;
  text-decoration: none;
  transition: top 0.2s ease;
}

.skip-link:focus { top: 0; text-decoration: none; }

/* ---------- 5. 命令栏（移动端优先：顶部粘性横条） ---------- */
.command-bar {
  position: sticky;
  top: 0;
  z-index: 120;
  width: 100%;
  background: var(--ink-deep);
  border-bottom: 1px solid var(--line);
}

.command-bar__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 10px 16px;
}

/* 品牌 */
.brand-mark {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  color: var(--text);
  text-decoration: none;
}

.brand-mark:hover { text-decoration: none; }

.brand-mark__glyph {
  flex: none;
  display: grid;
  place-items: center;
  width: 36px;
  height: 36px;
  background: linear-gradient(140deg, var(--cyan), var(--ok));
  color: #04121f;
  font-size: 17px;
  font-weight: 800;
  line-height: 1;
  clip-path: polygon(9px 0, 100% 0, 100% calc(100% - 9px), calc(100% - 9px) 100%, 0 100%, 0 9px);
}

.brand-mark__text {
  display: flex;
  flex-direction: column;
  line-height: 1.3;
}

.brand-mark__name { font-size: 15px; font-weight: 700; color: var(--text); }
.brand-mark__line { font-size: 11px; color: var(--muted); letter-spacing: 0.05em; }

/* 导航 */
.nav-cluster {
  position: absolute;
  top: 100%;
  left: 0;
  right: 0;
  display: none;
  padding: 16px 16px 22px;
  background: var(--ink-deep);
  border-bottom: 1px solid var(--line);
  box-shadow: 0 26px 44px rgba(0, 0, 0, 0.45);
}

.command-bar[data-open] .nav-cluster { display: block; }

.nav-cluster__list {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  list-style: none;
  margin: 0;
  padding: 0;
}

.nav-cluster__item { display: block; }

.nav-link {
  position: relative;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 9px 15px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: rgba(232, 240, 254, 0.03);
  color: var(--muted);
  font-size: 14px;
  font-weight: 600;
  text-decoration: none;
  transition: color 0.22s ease, border-color 0.22s ease, background-color 0.22s ease;
}

.nav-link:hover {
  color: var(--text);
  border-color: rgba(0, 229, 255, 0.4);
  background: rgba(0, 229, 255, 0.08);
  text-decoration: none;
}

.nav-link[aria-current="page"] {
  color: var(--cyan);
  border-color: rgba(0, 229, 255, 0.6);
  background: rgba(0, 229, 255, 0.12);
}

.nav-link__index {
  font-family: var(--font-mono);
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.14em;
  opacity: 0.7;
}

.nav-link__label {
  writing-mode: horizontal-tb;
  font-size: 14px;
  letter-spacing: 0.02em;
}

.nav-cluster__note {
  display: block;
  margin: 16px 0 0;
  color: var(--muted);
  font-size: 12.5px;
  letter-spacing: 0.06em;
}

/* 移动端隐藏桌面行动区 */
.command-bar__actions { display: none; }

/* 导航开关 */
.nav-toggle {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  padding: 8px 14px;
  border: 1px solid var(--line-strong);
  border-radius: 999px;
  color: var(--text);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.06em;
  transition: border-color 0.22s ease, color 0.22s ease;
}

.nav-toggle:hover { border-color: var(--cyan); color: var(--cyan); }

.nav-toggle__bars {
  position: relative;
  width: 18px;
  height: 2px;
  border-radius: 2px;
  background: var(--cyan);
  transition: background-color 0.2s ease;
}

.nav-toggle__bars::before,
.nav-toggle__bars::after {
  content: "";
  position: absolute;
  left: 0;
  width: 18px;
  height: 2px;
  border-radius: 2px;
  background: var(--cyan);
  transition: top 0.24s ease, transform 0.24s ease;
}

.nav-toggle__bars::before { top: -6px; }
.nav-toggle__bars::after { top: 6px; }

.command-bar[data-open] .nav-toggle__bars { background: transparent; }
.command-bar[data-open] .nav-toggle__bars::before { top: 0; transform: rotate(45deg); }
.command-bar[data-open] .nav-toggle__bars::after { top: 0; transform: rotate(-45deg); }

.nav-toggle__label { white-space: nowrap; }

/* 滚动进度 */
.scroll-progress {
  position: fixed;
  top: 0;
  left: 0;
  z-index: 140;
  width: var(--progress, 0%);
  height: 3px;
  background: linear-gradient(90deg, var(--cyan), var(--orange));
  pointer-events: none;
}

/* ---------- 6. 命令栏（桌面端：88px 左侧固定竖栏） ---------- */
@media (min-width: 960px) {
  body { padding-left: var(--rail); }

  .command-bar {
    position: fixed;
    top: 0;
    left: 0;
    bottom: 0;
    width: var(--rail);
    border-bottom: 0;
    border-right: 1px solid var(--line);
  }

  .command-bar__inner {
    flex-direction: column;
    align-items: center;
    justify-content: flex-start;
    gap: 18px;
    height: 100%;
    padding: 18px 10px 22px;
    overflow-y: auto;
    overflow-x: hidden;
    scrollbar-width: none;
  }

  .command-bar__inner::-webkit-scrollbar { width: 0; }

  .brand-mark__glyph { width: 46px; height: 46px; font-size: 21px; }
  .brand-mark__text { display: none; }

  .nav-cluster {
    position: static;
    display: block;
    width: 100%;
    padding: 0;
    background: none;
    border: 0;
    box-shadow: none;
  }

  .nav-cluster__list {
    flex-direction: column;
    flex-wrap: nowrap;
    gap: 4px;
  }

  .nav-cluster__item { width: 100%; }

  .nav-link {
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 5px;
    width: 100%;
    min-height: 72px;
    padding: 8px 4px;
    border-radius: var(--radius-sm);
    background: none;
    font-size: 12.5px;
  }

  .nav-link__index {
    font-size: 10px;
    letter-spacing: 0.16em;
    opacity: 0.65;
  }

  .nav-link__label {
    writing-mode: vertical-rl;
    text-orientation: upright;
    font-size: 12.5px;
    line-height: 1.15;
    letter-spacing: 0.12em;
  }

  .nav-link[aria-current="page"]::after {
    content: "";
    position: absolute;
    left: 3px;
    top: 50%;
    width: 2px;
    height: 22px;
    border-radius: 2px;
    background: var(--orange);
    transform: translateY(-50%);
  }

  .nav-cluster__note { display: none; }

  .command-bar__actions {
    display: flex;
    flex-direction: column;
    gap: 8px;
    width: 100%;
    margin-top: auto;
  }

  .command-bar__actions .btn {
    width: 100%;
    gap: 0;
    padding: 12px;
    border-radius: 12px;
    writing-mode: vertical-rl;
    text-orientation: upright;
    font-size: 12.5px;
    line-height: 1;
    letter-spacing: 0.16em;
  }

  .nav-toggle { display: none; }

  .scroll-progress {
    left: var(--rail);
    width: 3px;
    height: var(--progress, 0%);
    background: linear-gradient(180deg, var(--cyan), var(--orange));
  }
}

/* ---------- 7. 通用按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 22px;
  border: 1px solid transparent;
  border-radius: 999px;
  font-family: inherit;
  font-size: 14px;
  font-weight: 700;
  line-height: 1.3;
  letter-spacing: 0.03em;
  text-align: center;
  text-decoration: none;
  cursor: pointer;
  transition: background-color 0.22s ease, border-color 0.22s ease,
    color 0.22s ease, transform 0.22s ease;
}

.btn:hover { text-decoration: none; transform: translateY(-1px); }
.btn:active { transform: translateY(0); }

.btn--solid { background: var(--orange); color: #1b0b02; }
.btn--solid:hover { background: #ff8355; color: #1b0b02; }

.btn--ghost {
  background: rgba(0, 229, 255, 0.07);
  border-color: rgba(0, 229, 255, 0.45);
  color: var(--cyan);
}
.btn--ghost:hover { background: rgba(0, 229, 255, 0.16); border-color: var(--cyan); }

.btn--line { background: transparent; border-color: var(--line-strong); color: var(--text); }
.btn--line:hover { border-color: var(--cyan); color: var(--cyan); }

/* ---------- 8. 面板体系 ---------- */
.panel {
  position: relative;
  padding: clamp(20px, 3vw, 30px);
  background: var(--ink-soft);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  transition: transform 0.28s ease, border-color 0.28s ease, box-shadow 0.28s ease;
}

.panel:hover {
  transform: translateY(-4px);
  border-color: rgba(0, 229, 255, 0.5);
  box-shadow: var(--lift);
}

.panel--cut {
  border-radius: 0;
  clip-path: polygon(
    var(--cut) 0,
    100% 0,
    100% calc(100% - var(--cut)),
    calc(100% - var(--cut)) 100%,
    0 100%,
    0 var(--cut)
  );
}

.panel--cut:hover { transform: translateY(-2px); }

.panel--glass {
  background: rgba(20, 44, 78, 0.58);
  border-color: var(--line-strong);
  -webkit-backdrop-filter: blur(12px);
  backdrop-filter: blur(12px);
}

.panel--paper {
  background: var(--paper);
  border-color: rgba(10, 30, 60, 0.14);
  color: var(--ink);
}

.panel--paper:hover { border-color: rgba(10, 30, 60, 0.3); }

.panel__label {
  display: block;
  margin-bottom: 10px;
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.22em;
  color: var(--cyan);
}

.panel--paper .panel__label { color: #0a5f75; }

.panel__title {
  margin: 0 0 10px;
  font-size: clamp(19px, 2.2vw, 24px);
  font-weight: 800;
}

.panel--paper .panel__title { color: #06152c; }

/* ---------- 9. 区块索引头 ---------- */
.section-head {
  display: flex;
  flex-wrap: wrap;
  align-items: flex-end;
  gap: 8px 18px;
  margin-bottom: 26px;
}

.section-head__index {
  padding-bottom: 5px;
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.24em;
  color: var(--cyan);
}

.section-head__title {
  margin: 0;
  font-size: clamp(26px, 3.4vw, 34px);
}

.section-head__note {
  flex: 1 1 240px;
  padding-bottom: 6px;
  color: var(--muted);
  font-size: 14px;
}

/* ---------- 10. 标签与状态 ---------- */
.tag {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 5px 13px;
  border: 1px solid var(--line-strong);
  border-radius: 999px;
  color: var(--muted);
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.08em;
  white-space: nowrap;
}

.tag--live { color: var(--ok); border-color: rgba(43, 217, 168, 0.45); }
.tag--warn { color: var(--warn); border-color: rgba(255, 176, 32, 0.45); }

.status-dot {
  display: inline-block;
  flex: none;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--ok);
  box-shadow: 0 0 0 4px rgba(43, 217, 168, 0.16);
}

/* ---------- 11. 图片容器（供页面阶段放置图片） ---------- */
.figure-frame {
  position: relative;
  display: block;
  width: 100%;
  overflow: hidden;
  aspect-ratio: 16 / 9;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background-color: var(--ink-soft);
  background-image:
    radial-gradient(60% 70% at 24% 18%, rgba(0, 229, 255, 0.16), transparent 70%),
    radial-gradient(72% 62% at 86% 92%, rgba(255, 107, 53, 0.14), transparent 72%),
    linear-gradient(140deg, rgba(20, 44, 78, 0.92), rgba(7, 20, 41, 0.92));
}

.figure-frame--wide { aspect-ratio: 21 / 9; }
.figure-frame--tall { aspect-ratio: 3 / 4; }

.figure-frame > img,
.figure-frame > picture > img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.figure-frame__caption {
  position: absolute;
  left: 16px;
  right: 16px;
  bottom: 14px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.14em;
  color: var(--text);
  text-shadow: 0 1px 14px rgba(7, 20, 41, 0.95);
}

/* ---------- 12. 面包屑 ---------- */
.breadcrumbs { font-size: 12px; letter-spacing: 0.1em; }

.breadcrumbs__list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  list-style: none;
  margin: 0;
  padding: 0;
}

.breadcrumbs__item { display: inline-flex; align-items: center; gap: 8px; margin: 0; }
.breadcrumbs__sep { color: rgba(143, 166, 196, 0.5); }
.breadcrumbs__link { color: var(--muted); text-decoration: none; }
.breadcrumbs__link:hover { color: var(--cyan); text-decoration: none; }
.breadcrumbs__current { color: var(--text); }

/* ---------- 13. 正文排版 ---------- */
.prose {
  max-width: 34em;
  font-size: 17px;
  line-height: 1.8;
}

.prose > h2 { font-size: 27px; margin: 1.5em 0 0.55em; }
.prose > h3 { font-size: 21px; margin: 1.4em 0 0.5em; }
.prose > p { margin: 0 0 1.15em; }
.prose > ul,
.prose > ol { margin: 0 0 1.15em; padding-left: 1.3em; }

.prose > blockquote {
  margin: 1.4em 0;
  padding: 4px 0 4px 20px;
  border-left: 3px solid var(--cyan);
  color: var(--muted);
}

.panel--paper .prose { color: #0A1E3C; }
.panel--paper .prose h2,
.panel--paper .prose h3 { color: #06152c; }
.panel--paper .prose blockquote { color: #3b5578; }
.panel--paper .prose a { color: #0a5f75; }

/* ---------- 14. 页脚 ---------- */
.site-footer {
  position: relative;
  z-index: 1;
  margin-top: clamp(64px, 9vw, 120px);
  padding: 56px 0 34px;
  background: var(--ink-deep);
  border-top: 1px solid var(--line);
}

.site-footer::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--cyan), var(--orange), transparent);
  opacity: 0.55;
}

.site-footer::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background: linear-gradient(115deg, rgba(0, 229, 255, 0.06), transparent 46%, rgba(255, 107, 53, 0.05));
}

.site-footer__inner {
  position: relative;
  z-index: 1;
  width: 100%;
  max-width: var(--shell-max);
  margin-inline: auto;
  padding-inline: clamp(18px, 4vw, 32px);
}

.site-footer__top {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 40px;
}

@media (min-width: 860px) {
  .site-footer__top {
    grid-template-columns: 5fr 7fr;
    gap: 56px;
  }
}

.footer-brand {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.footer-brand__glyph {
  display: grid;
  place-items: center;
  width: 42px;
  height: 42px;
  background: linear-gradient(140deg, var(--cyan), var(--ok));
  color: #04121f;
  font-size: 19px;
  font-weight: 800;
  line-height: 1;
  clip-path: polygon(9px 0, 100% 0, 100% calc(100% - 9px), calc(100% - 9px) 100%, 0 100%, 0 9px);
}

.footer-brand__name {
  margin: 0;
  font-size: 20px;
  font-weight: 800;
  letter-spacing: 0.04em;
}

.footer-brand__slogan {
  margin: 0;
  max-width: 30ch;
  color: var(--muted);
  font-size: 15px;
  line-height: 1.8;
}

.footer-columns {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 28px;
}

@media (min-width: 560px) {
  .footer-columns { grid-template-columns: repeat(3, minmax(0, 1fr)); }
}

.footer-col__title {
  margin: 0 0 14px;
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.22em;
  color: var(--cyan);
}

.footer-links {
  display: flex;
  flex-direction: column;
  gap: 10px;
  list-style: none;
  margin: 0;
  padding: 0;
}

.footer-links li { margin: 0; }

.footer-links a {
  color: var(--muted);
  font-size: 14.5px;
  text-decoration: none;
  transition: color 0.2s ease;
}

.footer-links a:hover { color: var(--cyan); text-decoration: none; }

.site-footer__contact {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 34px;
  margin-top: 44px;
  padding-top: 24px;
  border-top: 1px solid var(--line);
}

.footer-contact__item {
  display: inline-flex;
  align-items: baseline;
  gap: 10px;
  margin: 0;
  font-size: 14px;
}

.footer-contact__key {
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.18em;
  color: var(--cyan);
}

.footer-contact__value { color: var(--text); }

.site-footer__service {
  margin: 12px 0 0;
  color: var(--muted);
  font-size: 12.5px;
  line-height: 1.7;
}

.site-footer__legal {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 8px 24px;
  margin-top: 26px;
  padding-top: 18px;
  border-top: 1px solid var(--line);
  color: rgba(143, 166, 196, 0.85);
  font-size: 12.5px;
}

.footer-legal__icp,
.footer-legal__meta { margin: 0; }

.footer-legal__icp { font-family: var(--font-mono); letter-spacing: 0.06em; }

/* ---------- 15. 返回顶部 ---------- */
.back-to-top {
  position: fixed;
  right: 20px;
  bottom: 20px;
  z-index: 130;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 17px;
  border: 1px solid rgba(0, 229, 255, 0.42);
  border-radius: 999px;
  background: rgba(7, 20, 41, 0.86);
  color: var(--cyan);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.04em;
  opacity: 0;
  visibility: hidden;
  transform: translateY(10px);
  transition: opacity 0.28s ease, transform 0.28s ease, visibility 0.28s ease,
    background-color 0.22s ease, border-color 0.22s ease;
  -webkit-backdrop-filter: blur(8px);
  backdrop-filter: blur(8px);
}

.back-to-top.is-visible {
  opacity: 1;
  visibility: visible;
  transform: none;
}

.back-to-top:hover {
  background: rgba(0, 229, 255, 0.16);
  border-color: var(--cyan);
}

.back-to-top__arrow { font-size: 15px; line-height: 1; }
.back-to-top__label { line-height: 1; }

/* ---------- 16. 入场动效 ---------- */
.js [data-reveal] {
  opacity: 0;
  transform: translateY(12px);
  transition:
    opacity 0.34s ease var(--reveal-delay, 0ms),
    transform 0.34s ease var(--reveal-delay, 0ms);
}

.js [data-reveal].is-visible {
  opacity: 1;
  transform: none;
}

/* ---------- 17. 无障碍与降级 ---------- */
@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;
  }

  .js [data-reveal] { opacity: 1; transform: none; }

  .back-to-top { transform: none; }
  .panel:hover,
  .btn:hover { transform: none; }
}

@media (max-width: 400px) {
  .nav-toggle__label { display: none; }
  .nav-link { font-size: 13px; padding: 8px 12px; }
  .back-to-top__label { display: none; }
  .back-to-top { padding: 11px 13px; border-radius: 50%; }
}