/* ==========================================================================
   火博看台 · 共享样式 /assets/site.css
   深夜看台的热浪 + 数据冷静：炭黑底、煤灰板、深焰橙结论、电光青数字
   ========================================================================== */

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

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

body {
  margin: 0;
  background: var(--ink);
  color: var(--white);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.75;
  letter-spacing: .01em;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

body,
button { font-family: var(--font-body); }

h1, h2, h3, h4, h5, h6 {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 900;
  line-height: 1.14;
  letter-spacing: -.02em;
}

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

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

/* ---------- 2. 变量 ---------- */
:root {
  /* 色板 */
  --ink: #0B0D10;
  --coal: #171A1F;
  --steel: #2A2F36;
  --white: #F4F6F8;
  --warm: #A9B0B8;
  --flame: #FF5A1F;
  --ember: #C63E0A;
  --cyan: #19D3E6;
  --teal: #0B7C8A;
  --green: #2FBF71;
  --warn: #FFC857;
  --warm-ink: #4F575F;      /* 冷白底上的次级文字 */

  /* 结构 */
  --line: 2px;
  --line-strong: 3px;
  --shell: 1280px;
  --gutter: clamp(18px, 4vw, 48px);
  --header-h: 72px;
  --ease: cubic-bezier(.22, .7, .28, 1);

  /* 硬阴影（现代粗野主义） */
  --shadow-hard: 8px 8px 0 rgba(0, 0, 0, .55);
  --shadow-flame: 8px 8px 0 rgba(255, 90, 31, .18);
  --shadow-cyan: 8px 8px 0 rgba(25, 211, 230, .16);

  /* 字体族（全部本地系统栈，无远程请求） */
  --font-display: "Noto Sans SC", "Source Han Sans SC", "PingFang SC", "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: "IBM Plex Mono", "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
}

/* ---------- 3. 容器与通用排版 ---------- */
.shell {
  width: min(calc(100% - var(--gutter) * 2), var(--shell));
  margin-inline: auto;
}

.shell--wide {
  width: min(calc(100% - var(--gutter) * 1.2), 1520px);
  margin-inline: auto;
}

.section { padding-block: clamp(48px, 8vw, 112px); }
.section--tight { padding-block: clamp(32px, 5vw, 64px); }

.section-head { margin-bottom: clamp(24px, 3.4vw, 48px); }

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .22em;
  text-transform: uppercase;
  color: var(--cyan);
}

.eyebrow::before {
  content: "";
  width: 26px;
  height: 2px;
  background: var(--flame);
  flex: 0 0 auto;
}

.section-title {
  margin: 14px 0 .4em;
  font-family: var(--font-display);
  font-weight: 900;
  font-size: clamp(28px, 4.4vw, 44px);
  line-height: 1.08;
  letter-spacing: -.025em;
}

.lede {
  max-width: 62ch;
  font-size: clamp(16px, 1.5vw, 20px);
  line-height: 1.7;
  color: var(--warm);
}

.rule {
  height: var(--line-strong);
  background: var(--steel);
  margin-block: clamp(28px, 5vw, 64px);
}

.rule--flame { background: var(--flame); height: var(--line); }

/* ---------- 4. 底纹分区 ---------- */
.surface-ink { background: var(--ink); color: var(--white); }
.surface-coal { background: var(--coal); color: var(--white); }
.surface-light { background: var(--white); color: var(--ink); }
.surface-light .lede,
.surface-light .prose { color: var(--warm-ink); }
.surface-light .section-title { color: var(--ink); }
.surface-light .rule { background: var(--steel); }

/* ---------- 5. 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 20px;
  font-size: 14px;
  font-weight: 600;
  line-height: 1;
  letter-spacing: .06em;
  border: var(--line) solid transparent;
  cursor: pointer;
  transition: transform .18s var(--ease), background-color .18s var(--ease),
              color .18s var(--ease), border-color .18s var(--ease), box-shadow .18s var(--ease);
}

.btn-primary {
  background: var(--flame);
  color: var(--ink);
  border-color: var(--flame);
  box-shadow: 4px 4px 0 rgba(0, 0, 0, .55);
}

.btn-primary:hover {
  background: var(--ember);
  border-color: var(--ember);
  color: var(--white);
  transform: translate(-2px, -2px);
  box-shadow: 6px 6px 0 rgba(0, 0, 0, .55);
}

.btn-ghost {
  background: transparent;
  color: var(--white);
  border-color: var(--steel);
}

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

.btn-outline {
  background: transparent;
  color: var(--white);
  border-color: var(--flame);
}

.btn-outline:hover {
  background: var(--flame);
  color: var(--ink);
}

.btn-quiet {
  background: var(--steel);
  color: var(--white);
  border-color: var(--steel);
}

.btn-quiet:hover { background: var(--teal); border-color: var(--teal); }

/* ---------- 6. 跳过链接 ---------- */
.skip-link {
  position: fixed;
  top: 0;
  left: 0;
  z-index: 200;
  padding: 12px 20px;
  background: var(--cyan);
  color: var(--ink);
  font-weight: 700;
  letter-spacing: .06em;
  transform: translateY(-160%);
  transition: transform .2s var(--ease);
}

.skip-link:focus { transform: translateY(0); }

#main-content:focus { outline: none; }

/* ---------- 7. 头部 ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 60;
  background: linear-gradient(180deg, rgba(11, 13, 16, .9) 0%, rgba(11, 13, 16, .62) 62%, rgba(11, 13, 16, 0) 100%);
  border-bottom: var(--line) solid transparent;
  backdrop-filter: blur(10px) saturate(140%);
  -webkit-backdrop-filter: blur(10px) saturate(140%);
  transition: background-color .28s var(--ease), border-color .28s var(--ease),
              box-shadow .28s var(--ease);
}

.site-header[data-scrolled="true"] {
  background: var(--coal);
  border-bottom-color: var(--steel);
  box-shadow: 0 2px 0 rgba(255, 90, 31, .85), 0 16px 34px rgba(0, 0, 0, .5);
}

.header-inner {
  width: min(calc(100% - var(--gutter) * 2), var(--shell));
  margin-inline: auto;
  min-height: var(--header-h);
  display: flex;
  align-items: center;
  gap: clamp(10px, 1.6vw, 26px);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  margin-right: auto;
  flex: 0 0 auto;
  color: var(--white);
}

.brand-mark {
  display: block;
  width: 14px;
  height: 34px;
  background: var(--flame);
  box-shadow: 5px 0 0 var(--cyan);
  transform: skewX(-10deg);
  flex: 0 0 auto;
}

.brand-text { display: block; }

.brand-name {
  display: block;
  font-family: var(--font-display);
  font-weight: 900;
  font-size: 20px;
  line-height: 1.15;
  letter-spacing: .06em;
}

.brand-sub {
  display: block;
  font-family: var(--font-mono);
  font-size: 11px;
  line-height: 1.4;
  letter-spacing: .06em;
  color: var(--warm);
}

.primary-nav {
  display: flex;
  align-items: center;
  gap: clamp(8px, 1.5vw, 22px);
}

.nav-list {
  display: flex;
  align-items: center;
  gap: clamp(6px, 1.3vw, 20px);
  list-style: none;
}

.nav-link {
  position: relative;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 2px;
  font-size: 14px;
  font-weight: 500;
  letter-spacing: .05em;
  color: var(--white);
  border-bottom: var(--line) solid transparent;
  transition: color .18s var(--ease), border-color .18s var(--ease);
}

.nav-link::before {
  content: "";
  width: 6px;
  height: 6px;
  background: var(--steel);
  flex: 0 0 auto;
  transition: background-color .18s var(--ease), box-shadow .18s var(--ease);
}

.nav-link:hover { color: var(--flame); }
.nav-link:hover::before { background: var(--flame); }

.nav-link[aria-current="page"] {
  color: var(--white);
  border-bottom-color: var(--flame);
}

.nav-link[aria-current="page"]::before {
  background: var(--cyan);
  box-shadow: 0 0 0 4px rgba(25, 211, 230, .18);
}

.nav-quick { display: none; }

.nav-quick-label {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: .2em;
  text-transform: uppercase;
  color: var(--warm);
}

.nav-quick-link {
  display: block;
  padding: 10px 12px;
  font-size: 14px;
  color: var(--cyan);
  border-left: var(--line) solid var(--steel);
}

.nav-quick-link:hover { border-left-color: var(--cyan); background: rgba(25, 211, 230, .06); }

.header-actions {
  display: flex;
  align-items: center;
  gap: 10px;
  flex: 0 0 auto;
}

.header-actions .btn { padding: 10px 16px; font-size: 13px; }

.nav-toggle {
  display: none;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 4px;
  width: 44px;
  height: 44px;
  border: var(--line) solid var(--steel);
  background: rgba(23, 26, 31, .8);
  cursor: pointer;
  flex: 0 0 auto;
}

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

.nav-toggle-bar {
  display: block;
  width: 20px;
  height: 2px;
  background: var(--white);
  transition: transform .22s var(--ease), opacity .22s var(--ease);
}

.nav-toggle[aria-expanded="true"] .nav-toggle-bar:nth-child(1) { transform: translateY(6px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] .nav-toggle-bar:nth-child(2) { opacity: 0; }
.nav-toggle[aria-expanded="true"] .nav-toggle-bar:nth-child(3) { transform: translateY(-6px) rotate(-45deg); }

.scroll-progress {
  position: absolute;
  left: 0;
  bottom: -2px;
  width: 100%;
  height: 3px;
  transform: scaleX(var(--progress, 0));
  transform-origin: left center;
  background: linear-gradient(90deg, var(--flame) 0%, var(--cyan) 100%);
  will-change: transform;
}

/* ---------- 8. 页脚 ---------- */
.site-footer {
  position: relative;
  margin-top: clamp(48px, 8vw, 120px);
  background: var(--coal);
  color: var(--white);
  border-top: var(--line-strong) solid var(--flame);
}

.footer-top {
  width: min(calc(100% - var(--gutter) * 2), var(--shell));
  margin-inline: auto;
  padding: clamp(44px, 6vw, 84px) 0 clamp(30px, 4vw, 52px);
  display: grid;
  grid-template-columns: minmax(0, 1.1fr) minmax(0, 1.5fr);
  gap: clamp(28px, 4vw, 72px);
}

.footer-mark {
  display: block;
  width: 12px;
  height: 28px;
  margin-bottom: 18px;
  background: var(--flame);
  box-shadow: 5px 0 0 var(--cyan);
  transform: skewX(-10deg);
}

.footer-brand-name {
  font-family: var(--font-display);
  font-weight: 900;
  font-size: 24px;
  letter-spacing: .08em;
}

.footer-brand-sub {
  margin-top: 4px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .08em;
  color: var(--cyan);
}

.footer-note {
  margin: 16px 0 24px;
  max-width: 34ch;
  font-size: 14px;
  line-height: 1.75;
  color: var(--warm);
}

.footer-cols {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: clamp(20px, 3vw, 48px);
}

.footer-col-title {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 18px;
  font-size: 15px;
  font-weight: 900;
  letter-spacing: .1em;
}

.footer-col-title::before {
  content: "";
  width: 10px;
  height: 10px;
  background: var(--flame);
  flex: 0 0 auto;
}

.footer-links { list-style: none; display: grid; gap: 10px; }

.footer-link {
  display: inline-block;
  font-size: 14px;
  color: var(--warm);
  border-bottom: 1px solid transparent;
  transition: color .18s var(--ease), border-color .18s var(--ease);
}

.footer-link:hover {
  color: var(--cyan);
  border-bottom-color: var(--cyan);
}

.footer-meta {
  width: min(calc(100% - var(--gutter) * 2), var(--shell));
  margin-inline: auto;
  padding: 22px 0 40px;
  border-top: var(--line) solid var(--steel);
  display: flex;
  flex-wrap: wrap;
  gap: 8px 32px;
  font-family: var(--font-mono);
  font-size: 12px;
  line-height: 1.85;
  letter-spacing: .02em;
  color: var(--warm);
}

.footer-contact { flex: 1 1 420px; }
.footer-legal { flex: 0 1 auto; color: var(--warm); }
.footer-copy { flex: 0 0 auto; margin-left: auto; color: var(--white); }

/* ---------- 9. 回到顶部 ---------- */
.to-top {
  position: fixed;
  right: clamp(14px, 3vw, 32px);
  bottom: clamp(14px, 3vw, 32px);
  z-index: 55;
  padding: 12px 16px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .16em;
  color: var(--white);
  background: var(--coal);
  border: var(--line) solid var(--flame);
  cursor: pointer;
  opacity: 0;
  transform: translateY(14px);
  pointer-events: none;
  transition: opacity .24s var(--ease), transform .24s var(--ease),
              background-color .18s var(--ease), color .18s var(--ease);
}

.to-top.is-visible {
  opacity: 1;
  transform: none;
  pointer-events: auto;
}

.to-top:hover { background: var(--flame); color: var(--ink); }

/* ---------- 10. 面板（堆叠画板） ---------- */
.panel {
  position: relative;
  padding: clamp(20px, 3vw, 36px);
  background: var(--coal);
  border: var(--line) solid var(--steel);
}

.panel-stack {
  display: grid;
  gap: clamp(18px, 2.6vw, 36px);
}

.panel--raised { box-shadow: var(--shadow-hard); }
.panel--flame { border-color: var(--flame); box-shadow: var(--shadow-flame); }
.panel--cyan { border-color: var(--cyan); box-shadow: var(--shadow-cyan); }

.panel--accent::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  width: 6px;
  height: 100%;
  background: var(--flame);
}

.surface-light .panel {
  background: #FFFFFF;
  border-color: var(--steel);
  color: var(--ink);
}

/* ---------- 11. 数据与状态 ---------- */
.figure {
  display: block;
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: clamp(32px, 6vw, 72px);
  line-height: .95;
  letter-spacing: -.03em;
  font-variant-numeric: tabular-nums;
  color: var(--white);
}

.figure--cyan { color: var(--cyan); }
.figure--flame { color: var(--flame); }

.figure-label {
  display: block;
  margin-top: 10px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: .2em;
  text-transform: uppercase;
  color: var(--warm);
}

.surface-light .figure { color: var(--ink); }
.surface-light .figure--cyan { color: var(--teal); }
.surface-light .figure--flame { color: var(--ember); }
.surface-light .figure-label { color: var(--warm-ink); }

.data-strip {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: clamp(14px, 2vw, 28px);
  padding: clamp(16px, 2.4vw, 28px) 0;
  border-top: var(--line) solid var(--steel);
  border-bottom: var(--line) solid var(--steel);
}

.data-cell { min-width: 0; }

.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 5px 10px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: .1em;
  color: var(--warm);
  border: 1px solid var(--steel);
  background: rgba(244, 246, 248, .03);
}

.tag--live { color: var(--ink); background: var(--flame); border-color: var(--flame); }
.tag--ok { color: var(--green); border-color: rgba(47, 191, 113, .55); }
.tag--warn { color: var(--warn); border-color: rgba(255, 200, 87, .55); }
.tag--data { color: var(--cyan); border-color: rgba(25, 211, 230, .45); }

.dot {
  display: inline-block;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--green);
  flex: 0 0 auto;
}

.dot--live {
  background: var(--flame);
  box-shadow: 0 0 0 4px rgba(255, 90, 31, .2);
}

/* ---------- 12. 图片容器 ---------- */
.media-frame {
  position: relative;
  overflow: hidden;
  aspect-ratio: 16 / 9;
  background: var(--coal);
  border: var(--line) solid var(--steel);
}

.media-frame img {
  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 figcaption {
  position: absolute;
  left: 0;
  bottom: 0;
  padding: 8px 12px;
  background: rgba(11, 13, 16, .82);
  color: var(--white);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: .08em;
}

/* ---------- 13. 栅格 ---------- */
.grid {
  display: grid;
  gap: clamp(16px, 2.4vw, 32px);
}

.grid-2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid-3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid-4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }

/* ---------- 14. 面包屑 ---------- */
.breadcrumb {
  padding-block: 18px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .06em;
}

.breadcrumb ol {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  list-style: none;
}

.breadcrumb li { display: inline-flex; align-items: center; gap: 10px; }

.breadcrumb li::after {
  content: "/";
  color: var(--steel);
}

.breadcrumb li:last-child::after { content: ""; }

.breadcrumb a { color: var(--warm); }
.breadcrumb a:hover { color: var(--cyan); }
.breadcrumb [aria-current="page"] { color: var(--white); }
.surface-light .breadcrumb [aria-current="page"] { color: var(--ink); }

/* ---------- 15. 正文容器 ---------- */
.prose {
  max-width: 72ch;
  font-size: 16px;
  line-height: 1.75;
  color: inherit;
}

.prose > * + * { margin-top: 1.1em; }

.prose h2 {
  margin-top: 1.7em;
  font-size: clamp(22px, 2.6vw, 28px);
}

.prose h3 {
  margin-top: 1.5em;
  font-size: 20px;
}

.prose ul,
.prose ol {
  padding-left: 1.35em;
}

.prose ul li { list-style: square; }
.prose ol li { list-style: decimal; }
.prose li { margin-block: .35em; }

.prose a {
  color: var(--cyan);
  border-bottom: 1px solid currentColor;
}

.prose a:hover { color: var(--flame); }

.surface-light .prose a { color: var(--ember); }
.surface-light .prose h2,
.surface-light .prose h3 { color: var(--ink); }

.prose blockquote {
  margin-inline: 0;
  padding: 4px 0 4px 20px;
  border-left: 4px solid var(--flame);
  color: var(--warm);
}

/* ---------- 16. 可展开内容组 ---------- */
.accordion {
  border-top: var(--line) solid var(--steel);
}

.accordion-item {
  border-bottom: var(--line) solid var(--steel);
}

.accordion-trigger {
  display: flex;
  width: 100%;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  padding: 20px 4px;
  font-size: 16px;
  font-weight: 600;
  line-height: 1.5;
  text-align: left;
  cursor: pointer;
  transition: color .18s var(--ease);
}

.accordion-trigger:hover { color: var(--cyan); }

.accordion-trigger::after {
  content: "";
  width: 11px;
  height: 11px;
  flex: 0 0 auto;
  border-right: 2px solid var(--cyan);
  border-bottom: 2px solid var(--cyan);
  transform: rotate(45deg);
  transition: transform .24s var(--ease);
}

.accordion-trigger[aria-expanded="true"]::after { transform: rotate(-135deg); }

.accordion-panel {
  height: 0;
  overflow: hidden;
  transition: height .3s var(--ease);
}

.accordion-panel-inner {
  padding: 0 4px 24px;
  max-width: 72ch;
  color: var(--warm);
  line-height: 1.75;
}

.surface-light .accordion-panel-inner { color: var(--warm-ink); }

/* ---------- 17. 显现动画（需 JS 开启 .js-enabled） ---------- */
.js-enabled [data-reveal] {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity .42s var(--ease), transform .42s var(--ease);
}

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

/* ---------- 18. 折叠菜单与断点 ---------- */
@media (max-width: 1079px) {
  .nav-toggle { display: inline-flex; }

  body.nav-open { overflow: hidden; }

  .primary-nav {
    position: fixed;
    top: var(--header-h);
    left: 0;
    right: 0;
    z-index: 59;
    display: none;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    margin: 0;
    padding: 8px var(--gutter) 30px;
    max-height: calc(100vh - var(--header-h));
    overflow-y: auto;
    background: var(--coal);
    border-bottom: var(--line-strong) solid var(--flame);
    box-shadow: 0 26px 48px rgba(0, 0, 0, .6);
  }

  .primary-nav[data-open] {
    display: flex;
    animation: nav-drop .26s var(--ease);
  }

  .nav-list {
    flex-direction: column;
    align-items: stretch;
    gap: 0;
  }

  .nav-item { border-bottom: var(--line) solid var(--steel); }

  .nav-link {
    padding: 16px 2px;
    font-size: 17px;
    font-weight: 700;
    border-bottom: 0;
  }

  .nav-link::before { width: 8px; height: 8px; }

  .nav-quick {
    display: grid;
    gap: 8px;
    padding-top: 22px;
  }

  .nav-quick-label { margin-bottom: 4px; }
}

@keyframes nav-drop {
  from { opacity: 0; transform: translateY(-10px); }
  to { opacity: 1; transform: none; }
}

@media (max-width: 960px) {
  .grid-3,
  .grid-4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }

  .footer-top { grid-template-columns: minmax(0, 1fr); }
}

@media (max-width: 900px) {
  .header-actions .btn-ghost { display: none; }

  .footer-copy { margin-left: 0; }
}

@media (max-width: 720px) {
  :root { --header-h: 64px; }

  .brand-mark { height: 28px; }
  .brand-name { font-size: 18px; }

  .grid-2,
  .grid-3,
  .grid-4 { grid-template-columns: minmax(0, 1fr); }

  .footer-cols { grid-template-columns: minmax(0, 1fr); }
}

@media (max-width: 560px) {
  .brand-sub { display: none; }
  .header-actions .btn { padding: 10px 12px; font-size: 12px; letter-spacing: .02em; }
  .brand { gap: 10px; }
  .brand-mark { box-shadow: 4px 0 0 var(--cyan); }
}

/* ---------- 19. 无障碍与动效偏好 ---------- */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }

  *,
  *::before,
  *::after {
    animation-duration: .001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: .001ms !important;
    scroll-behavior: auto !important;
  }

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

  .primary-nav[data-open] { animation: none; }
}