/* ============================================================
   IM 中文站 · 共享样式 /assets/site.css
   夜间赛场数据画册：深空底、细网格、章节编号、霓虹数据点
   ============================================================ */

:root {
  --ink: #060A18;
  --panel: #0D152B;
  --line: #16223F;
  --cyan: #2FF3D6;
  --blue: #4DA3FF;
  --orange: #FF7A2F;
  --purple: #8B5CF6;
  --text: #E9F0FF;
  --text-soft: #C6D2EA;
  --muted: #8FA0BE;
  --paper: #F3F5F9;
  --shell: 1240px;
  --gutter: clamp(18px, 4vw, 56px);
  --header-h: 96px;
  --radius: 2px;
  --font-display: "Barlow Condensed", "Oswald", "Arial Narrow", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --font-body: "PingFang SC", "Hiragino Sans GB", "Source Han Sans SC", "Microsoft YaHei", system-ui, -apple-system, "Segoe UI", sans-serif;
  --font-mono: "JetBrains Mono", "Roboto Mono", "SFMono-Regular", Menlo, Consolas, monospace;
}

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

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

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

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

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

button, input, select, textarea { font: inherit; color: inherit; }

button { background: none; border: 0; }

a { color: inherit; text-decoration: none; }

[hidden] { display: none !important; }

::selection {
  background: var(--cyan);
  color: #04110E;
}

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

/* ---------- 基础排版 ---------- */
body {
  min-height: 100vh;
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.7;
  color: var(--text);
  background-color: var(--ink);
  background-image:
    radial-gradient(1100px 560px at 88% -8%, rgba(77, 163, 255, 0.16), transparent 62%),
    radial-gradient(900px 520px at -8% 26%, rgba(139, 92, 246, 0.12), transparent 66%),
    linear-gradient(to bottom, rgba(22, 34, 63, 0.38) 1px, transparent 1px),
    linear-gradient(to right, rgba(22, 34, 63, 0.28) 1px, transparent 1px);
  background-repeat: no-repeat, no-repeat, repeat, repeat;
  background-size: auto, auto, 100% 120px, 120px 100%;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

h1, h2, h3, h4 {
  font-family: var(--font-display);
  font-weight: 800;
  line-height: 1.05;
  letter-spacing: -0.01em;
}

p { color: inherit; }

strong, b { font-weight: 700; color: #FFFFFF; }

#main-content { scroll-margin-top: calc(var(--header-h) + 12px); }

.page-main { padding-top: var(--header-h); }

.page-main[data-hero] { padding-top: 0; }

.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;
}

/* ---------- 布局 ---------- */
.shell {
  width: 100%;
  max-width: var(--shell);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.grid-12 {
  display: grid;
  grid-template-columns: repeat(12, minmax(0, 1fr));
  gap: clamp(16px, 2vw, 32px);
}

.col-2 { grid-column: span 2; }
.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-12 { grid-column: span 12; }

/* ---------- 标题与文字层级 ---------- */
.display-title {
  font-family: var(--font-display);
  font-size: clamp(42px, 7.4vw, 76px);
  font-weight: 800;
  line-height: 0.94;
  letter-spacing: -0.02em;
  color: var(--text);
}

.section-head {
  display: flex;
  flex-wrap: wrap;
  align-items: flex-end;
  justify-content: space-between;
  gap: 14px 28px;
  padding-bottom: 18px;
  margin-bottom: clamp(22px, 3vw, 38px);
  border-bottom: 1px solid var(--line);
}

.section-title {
  font-size: clamp(28px, 4vw, 40px);
  line-height: 1.02;
  letter-spacing: -0.02em;
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--cyan);
}

.eyebrow::before {
  content: "";
  width: 18px;
  height: 1px;
  background: var(--cyan);
  box-shadow: 0 0 10px rgba(47, 243, 214, 0.7);
}

.lede {
  max-width: 62ch;
  font-size: clamp(15px, 1.3vw, 18px);
  line-height: 1.8;
  color: var(--text-soft);
}

.rule {
  height: 1px;
  margin: clamp(28px, 4vw, 48px) 0;
  border: 0;
  background: linear-gradient(90deg, var(--line), rgba(47, 243, 214, 0.35), var(--line));
}

/* ---------- 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 11px 18px;
  border: 1px solid transparent;
  border-radius: var(--radius);
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.1em;
  line-height: 1.2;
  cursor: pointer;
  transition: background-color 160ms ease, border-color 160ms ease, color 160ms ease, transform 160ms ease;
}

.btn-cta {
  background: var(--orange);
  color: #170A02;
  font-weight: 700;
  box-shadow: 0 10px 30px rgba(255, 122, 47, 0.18);
}

.btn-cta:hover {
  background: #FF9152;
  transform: translateY(-1px);
}

.btn-ghost {
  border-color: var(--line);
  background: rgba(13, 21, 43, 0.6);
  color: var(--text);
}

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

/* ---------- 标签 / 胶囊 ---------- */
.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 9px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: rgba(13, 21, 43, 0.72);
  font-family: var(--font-mono);
  font-size: 10px;
  font-weight: 500;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--muted);
  white-space: nowrap;
}

.tag--cyan {
  border-color: rgba(47, 243, 214, 0.45);
  color: var(--cyan);
  background: rgba(47, 243, 214, 0.08);
}

/* ---------- 卡片 ---------- */
.card {
  position: relative;
  padding: clamp(18px, 2.4vw, 30px);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--panel);
}

.card--stack {
  box-shadow:
    6px 6px 0 rgba(22, 34, 63, 0.92),
    6px 6px 0 1px rgba(47, 243, 214, 0.14);
}

.card--paper {
  background: var(--paper);
  border-color: #CFD8E8;
  color: #0A1224;
}

.card-title {
  font-family: var(--font-display);
  font-size: 22px;
  font-weight: 800;
  letter-spacing: -0.01em;
  line-height: 1.15;
}

.card-meta {
  margin-top: 10px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.12em;
  color: var(--muted);
}

.card--paper .card-meta { color: #4C5C7A; }

/* ---------- 数据组件 ---------- */
.stat {
  display: grid;
  gap: 4px;
}

.stat-value {
  font-family: var(--font-mono);
  font-size: clamp(32px, 5vw, 56px);
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  line-height: 1;
  letter-spacing: -0.03em;
  color: var(--orange);
}

.stat-label {
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--muted);
}

/* ---------- 响应式图片容器 ---------- */
.media {
  position: relative;
  overflow: hidden;
  aspect-ratio: var(--ratio, 16 / 9);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background:
    radial-gradient(120% 120% at 80% 0%, rgba(77, 163, 255, 0.18), transparent 60%),
    linear-gradient(135deg, var(--panel), #0A1024);
}

.media img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  filter: saturate(0.92) contrast(1.06);
}

.media::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background-image:
    linear-gradient(rgba(47, 243, 214, 0.1) 1px, transparent 1px),
    linear-gradient(90deg, rgba(47, 243, 214, 0.1) 1px, transparent 1px);
  background-size: 100% 56px, 56px 100%;
  mix-blend-mode: screen;
  opacity: 0.55;
}

.media--wide { --ratio: 21 / 9; }
.media--tall { --ratio: 3 / 4; }
.media--square { --ratio: 1 / 1; }

.media-tag {
  position: absolute;
  left: 12px;
  bottom: 12px;
  z-index: 2;
  padding: 6px 9px;
  background: rgba(47, 243, 214, 0.92);
  color: #04110E;
  font-family: var(--font-mono);
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.16em;
  text-transform: uppercase;
}

/* ---------- 筛选 ---------- */
.filter-bar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
}

.filter-btn {
  appearance: none;
  padding: 8px 14px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: rgba(13, 21, 43, 0.65);
  color: var(--text-soft);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.12em;
  cursor: pointer;
  transition: border-color 160ms ease, color 160ms ease, background-color 160ms ease, box-shadow 160ms ease;
}

.filter-btn:hover {
  border-color: rgba(47, 243, 214, 0.5);
  color: var(--cyan);
}

.filter-btn[aria-pressed="true"] {
  border-color: var(--cyan);
  color: var(--cyan);
  background: rgba(47, 243, 214, 0.08);
  box-shadow: inset 0 0 0 1px rgba(47, 243, 214, 0.22), 0 0 18px rgba(47, 243, 214, 0.12);
}

.filter-meta {
  margin-left: auto;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.14em;
  color: var(--muted);
}

.empty-state {
  padding: clamp(24px, 4vw, 44px);
  border: 1px dashed var(--line);
  border-radius: var(--radius);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--muted);
  text-align: center;
}

/* ---------- 面包屑 ---------- */
.breadcrumb {
  margin-bottom: clamp(20px, 3vw, 32px);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--muted);
}

.breadcrumb-list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
}

.breadcrumb-item {
  display: inline-flex;
  align-items: center;
  gap: 8px;
}

.breadcrumb-item + .breadcrumb-item::before {
  content: "/";
  color: var(--line);
}

.breadcrumb-link {
  color: var(--text-soft);
  border-bottom: 1px solid transparent;
  transition: color 160ms ease, border-color 160ms ease;
}

.breadcrumb-link:hover {
  color: var(--cyan);
  border-bottom-color: rgba(47, 243, 214, 0.5);
}

/* ---------- 长页正文与目录 ---------- */
.prose {
  max-width: 68ch;
  color: var(--text-soft);
}

.prose > * + * { margin-top: 1.05em; }

.prose h2 {
  margin-top: 2em;
  font-size: clamp(24px, 3vw, 32px);
  color: var(--text);
}

.prose h3 {
  margin-top: 1.6em;
  font-size: 20px;
  color: var(--text);
}

.prose ul,
.prose ol {
  padding-left: 1.25em;
  list-style: disc;
}

.prose ol { list-style: decimal; }

.prose li + li { margin-top: 0.4em; }

.prose a {
  color: var(--cyan);
  border-bottom: 1px solid rgba(47, 243, 214, 0.35);
}

.prose blockquote {
  padding: 14px 18px;
  border-left: 2px solid var(--cyan);
  background: rgba(13, 21, 43, 0.7);
  color: var(--text);
}

.toc {
  position: sticky;
  top: calc(var(--header-h) + 24px);
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: rgba(13, 21, 43, 0.72);
}

.toc-title {
  font-family: var(--font-mono);
  font-size: 10px;
  font-weight: 600;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--cyan);
  margin-bottom: 12px;
}

.toc-list { display: grid; gap: 8px; }

.toc-link {
  display: block;
  font-size: 13px;
  line-height: 1.5;
  color: var(--muted);
  border-left: 1px solid var(--line);
  padding-left: 10px;
  transition: color 160ms ease, border-color 160ms ease;
}

.toc-link:hover { color: var(--text); }

.toc-link[aria-current="true"] {
  color: var(--cyan);
  border-left-color: var(--cyan);
}

/* ---------- 滚动显现 ---------- */
@media (prefers-reduced-motion: no-preference) {
  .reveal {
    opacity: 0;
    transform: translateY(14px);
    transition: opacity 520ms ease, transform 520ms ease;
  }

  .reveal.is-in {
    opacity: 1;
    transform: none;
  }
}

/* ---------- 跳转链接 ---------- */
.skip-link {
  position: fixed;
  top: 10px;
  left: 10px;
  z-index: 300;
  padding: 10px 16px;
  border-radius: var(--radius);
  background: var(--cyan);
  color: #04110E;
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.08em;
  transform: translateY(-180%);
  transition: transform 180ms ease;
}

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

/* ---------- 页头 ---------- */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  color: var(--text);
  background: transparent;
  border-bottom: 1px solid transparent;
  transition: background-color 240ms ease, border-color 240ms ease, backdrop-filter 240ms ease;
}

.site-header[data-scrolled="true"],
.site-header[data-open="true"] {
  background: rgba(6, 10, 24, 0.94);
  border-bottom-color: var(--line);
  -webkit-backdrop-filter: blur(14px) saturate(140%);
  backdrop-filter: blur(14px) saturate(140%);
}

.header-rail {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  height: 24px;
  padding-inline: var(--gutter);
  border-bottom: 1px solid rgba(22, 34, 63, 0.7);
  background:
    repeating-linear-gradient(90deg, rgba(47, 243, 214, 0.35) 0 1px, transparent 1px 24px) left bottom / 100% 3px no-repeat;
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--muted);
}

.header-rail-label { color: var(--cyan); }

.header-rail-meta { color: var(--muted); }

.header-inner {
  display: flex;
  align-items: center;
  gap: clamp(12px, 2vw, 28px);
  width: 100%;
  max-width: var(--shell);
  height: 72px;
  margin-inline: auto;
  padding-inline: var(--gutter);
}

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

.brand-mark {
  display: grid;
  place-items: center;
  width: 44px;
  height: 44px;
  border: 1px solid rgba(47, 243, 214, 0.5);
  border-radius: var(--radius);
  background: linear-gradient(145deg, rgba(13, 21, 43, 0.95), rgba(6, 10, 24, 0.95));
  box-shadow: inset 0 0 0 1px rgba(47, 243, 214, 0.12), 0 0 24px rgba(47, 243, 214, 0.12);
  color: var(--cyan);
  font-family: var(--font-mono);
  font-size: 15px;
  font-weight: 700;
  letter-spacing: 0.04em;
}

.brand-text {
  display: grid;
  gap: 2px;
}

.brand-name {
  font-family: var(--font-display);
  font-size: 19px;
  font-weight: 800;
  line-height: 1.1;
  letter-spacing: 0.02em;
  color: var(--text);
}

.brand-tag {
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.12em;
  color: var(--muted);
}

.site-nav {
  display: flex;
  align-items: center;
  gap: 18px;
  margin-left: auto;
}

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

.nav-link {
  position: relative;
  display: inline-flex;
  flex-direction: column;
  gap: 2px;
  padding: 10px 2px;
  font-size: 14px;
  line-height: 1.2;
  letter-spacing: 0.02em;
  color: var(--text);
  white-space: nowrap;
}

.nav-idx {
  font-family: var(--font-mono);
  font-size: 9px;
  line-height: 1;
  letter-spacing: 0.18em;
  color: var(--muted);
  transition: color 160ms ease;
}

.nav-link::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 1px;
  height: 1px;
  background: var(--cyan);
  transform: scaleX(0);
  transform-origin: 0 50%;
  transition: transform 180ms ease;
}

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

.nav-link:hover .nav-idx { color: var(--cyan); }

.nav-link:hover::after { transform: scaleX(1); }

.nav-link[aria-current="page"] { color: var(--cyan); }

.nav-link[aria-current="page"] .nav-idx { color: var(--cyan); }

.nav-link[aria-current="page"]::after {
  transform: scaleX(1);
  box-shadow: 0 0 12px rgba(47, 243, 214, 0.7);
}

.nav-cta { display: none; }

.header-actions {
  position: relative;
  z-index: 2;
  display: flex;
  align-items: center;
  gap: 10px;
  margin-left: 6px;
}

.header-cta { padding: 10px 14px; }

.nav-toggle {
  display: none;
  align-items: center;
  gap: 8px;
  padding: 9px 12px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: rgba(13, 21, 43, 0.65);
  color: var(--text);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  cursor: pointer;
  transition: border-color 160ms ease, color 160ms ease;
}

.nav-toggle:hover {
  border-color: rgba(47, 243, 214, 0.5);
  color: var(--cyan);
}

.nav-toggle-bars {
  display: grid;
  gap: 5px;
  width: 18px;
}

.nav-toggle-bars span {
  display: block;
  height: 1px;
  background: currentColor;
  transition: transform 180ms ease, opacity 180ms ease;
}

.nav-toggle[aria-expanded="true"] .nav-toggle-bars span:first-child {
  transform: translateY(3px) rotate(45deg);
}

.nav-toggle[aria-expanded="true"] .nav-toggle-bars span:last-child {
  transform: translateY(-3px) rotate(-45deg);
}

.scroll-progress {
  position: absolute;
  left: 0;
  right: 0;
  bottom: -1px;
  height: 2px;
  background: linear-gradient(90deg, var(--cyan), var(--blue), var(--purple));
  transform: scaleX(0);
  transform-origin: 0 50%;
  pointer-events: none;
}

/* ---------- 页脚 ---------- */
.site-footer {
  position: relative;
  margin-top: clamp(64px, 9vw, 140px);
  border-top: 1px solid var(--line);
  background:
    radial-gradient(900px 340px at 8% 0%, rgba(77, 163, 255, 0.1), transparent 62%),
    linear-gradient(180deg, rgba(13, 21, 43, 0.72), rgba(6, 10, 24, 1) 46%);
}

.site-footer::before {
  content: "";
  display: block;
  height: 6px;
  background: repeating-linear-gradient(90deg, var(--line) 0 1px, transparent 1px 18px);
}

.footer-inner {
  width: 100%;
  max-width: var(--shell);
  margin-inline: auto;
  padding: clamp(36px, 5vw, 72px) var(--gutter) 0;
}

.footer-top {
  display: grid;
  grid-template-columns: 1.1fr 1.5fr 0.9fr;
  gap: clamp(28px, 4vw, 64px);
}

.footer-brand-link {
  display: inline-flex;
  align-items: center;
  gap: 10px;
}

.footer-mark {
  display: grid;
  place-items: center;
  width: 36px;
  height: 36px;
  border: 1px solid rgba(47, 243, 214, 0.45);
  border-radius: var(--radius);
  background: rgba(13, 21, 43, 0.9);
  color: var(--cyan);
  font-family: var(--font-mono);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.04em;
}

.footer-brand-name {
  font-family: var(--font-display);
  font-size: 20px;
  font-weight: 800;
  letter-spacing: 0.02em;
  color: var(--text);
}

.footer-lead {
  max-width: 34ch;
  margin: 14px 0 18px;
  font-size: 14px;
  line-height: 1.75;
  color: var(--text-soft);
}

.footer-cta {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding-bottom: 4px;
  border-bottom: 1px solid rgba(47, 243, 214, 0.4);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.12em;
  color: var(--cyan);
  transition: color 160ms ease, border-color 160ms ease;
}

.footer-cta:hover {
  color: #FFFFFF;
  border-bottom-color: #FFFFFF;
}

.footer-nav {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 24px;
}

.footer-col-title {
  margin-bottom: 14px;
  font-family: var(--font-mono);
  font-size: 10px;
  font-weight: 600;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--cyan);
}

.footer-list {
  display: grid;
  gap: 9px;
}

.footer-link {
  font-size: 14px;
  line-height: 1.5;
  color: var(--text-soft);
  transition: color 160ms ease;
}

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

.contact-list {
  display: grid;
  gap: 10px;
}

.contact-item {
  display: grid;
  grid-template-columns: 44px minmax(0, 1fr);
  gap: 8px;
  align-items: baseline;
}

.contact-label {
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--muted);
}

.contact-value {
  font-size: 13px;
  line-height: 1.6;
  color: var(--text-soft);
  overflow-wrap: anywhere;
}

.footer-note {
  margin-top: 14px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  color: var(--muted);
}

.footer-bottom {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 8px 24px;
  margin-top: clamp(32px, 4vw, 56px);
  padding-block: 22px;
  border-top: 1px solid var(--line);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  color: var(--muted);
}

/* ---------- 平板与移动端 ---------- */
@media (max-width: 1039px) {
  :root { --header-h: 64px; }

  .header-rail { display: none; }

  .header-inner { height: 64px; }

  .nav-toggle { display: inline-flex; }

  .site-nav {
    position: fixed;
    top: var(--header-h);
    left: 0;
    right: 0;
    display: flex;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    max-height: calc(100vh - var(--header-h));
    margin-left: 0;
    padding: 18px var(--gutter) 30px;
    overflow-y: auto;
    background: linear-gradient(180deg, rgba(13, 21, 43, 0.99), rgba(6, 10, 24, 0.99));
    border-bottom: 1px solid var(--line);
    opacity: 0;
    visibility: hidden;
    transform: translateY(-8px);
    transition: opacity 200ms ease, transform 200ms ease, visibility 200ms ease;
  }

  .site-header[data-open="true"] .site-nav {
    opacity: 1;
    visibility: visible;
    transform: none;
  }

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

  .nav-link {
    flex-direction: row;
    align-items: baseline;
    gap: 12px;
    padding: 16px 0;
    border-bottom: 1px solid var(--line);
    font-size: 17px;
  }

  .nav-idx { font-size: 11px; }

  .nav-link::after { display: none; }

  .nav-link[aria-current="page"] {
    color: var(--cyan);
  }

  .nav-cta {
    display: inline-flex;
    align-self: flex-start;
    margin-top: 20px;
  }

  .has-nav-open { overflow: hidden; }
}

@media (max-width: 900px) {
  .footer-top { grid-template-columns: 1fr 1fr; }

  .footer-brand { grid-column: 1 / -1; }

  .footer-contact {
    grid-column: 1 / -1;
    padding-top: 20px;
    border-top: 1px solid var(--line);
  }
}

@media (max-width: 860px) {
  .col-2,
  .col-3,
  .col-4,
  .col-5 { grid-column: span 6; }

  .col-7,
  .col-8 { grid-column: span 12; }

  .toc {
    position: static;
  }
}

@media (max-width: 640px) {
  .col-2,
  .col-3,
  .col-4,
  .col-5,
  .col-6,
  .col-7,
  .col-8 { grid-column: span 12; }

  .brand-tag { display: none; }

  .header-cta { display: none; }

  .footer-top { grid-template-columns: 1fr; }

  .footer-nav { grid-template-columns: 1fr 1fr; }

  .footer-bottom { justify-content: flex-start; }

  .filter-meta { margin-left: 0; }
}

@media (max-width: 420px) {
  .brand-mark {
    width: 38px;
    height: 38px;
    font-size: 13px;
  }

  .brand-name { font-size: 17px; }

  .nav-toggle { padding: 8px 10px; }

  .footer-nav { grid-template-columns: 1fr; }
}

/* ---------- 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;
  }

  .reveal {
    opacity: 1;
    transform: none;
  }
}