:root {
  --color-surface: #fefefe;
  --color-surface-alt: #f5f5f6;
  --color-surface-deep: #e8e9ea;
  --color-ink: #494b55;
  --color-ink-soft: #6d707e;
  --color-ink-muted: #787b87;
  --color-line: #dddee0;
  --color-primary: #3553ca;
  --color-primary-ink: #ffffff;
  --color-primary-soft: #e2e6f7;
  --color-accent: #e12919;
  --color-accent-ink: #ffffff;
  --color-highlight: #f9d8d5;
  --color-focus: #e41d0c;
  --color-contrast-surface: #10121b;
  --color-contrast-ink: #e4e5e7;
  --color-contrast-line: #3f4048;
  --color-contrast-accent: #e83b2c;
  --overlay-scrim: linear-gradient(180deg, rgba(16, 18, 27, 0.35) 0%, rgba(16, 18, 27, 0.72) 55%, rgba(16, 18, 27, 0.92) 100%);
  --font-heading: "PingFang SC", "HarmonyOS Sans SC", "Microsoft YaHei", "Source Han Sans SC", sans-serif;
  --font-body: "PingFang SC", "HarmonyOS Sans SC", "Microsoft YaHei", "Source Han Sans SC", sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  --text-xs: 11.4px;
  --text-sm: 13.7px;
  --text-base: 15px;
  --text-lg: 18.0px;
  --text-xl: 21.6px;
  --text-2xl: 25.9px;
  --text-3xl: 31.1px;
  --text-4xl: 37.3px;
  --text-display: clamp(34px, 5.7vw, 73px);
  --text-figure: clamp(28px, 4.1vw, 53px);
  --weight-heading: 693;
  --weight-body: 400;
  --leading-body: 1.74;
  --leading-heading: 1.27;
  --tracking-heading: -0.005em;
  --radius-sm: 8px;
  --radius-md: 10px;
  --radius-lg: 13px;
  --radius-pill: 999px;
  --border-thin: 1px;
  --border-thick: 1px;
  --shadow-1: 0 6px 18px rgba(73, 75, 85, 0.08);
  --shadow-2: 0 18px 44px rgba(73, 75, 85, 0.14);
  --space-1: 7px;
  --space-2: 14px;
  --space-3: 21px;
  --space-4: 28px;
  --space-6: 42px;
  --space-8: 56px;
  --container: 1300px;
  --measure: 71ch;
  --gutter: 28px;
  --section-y: 58px;
  --section-y-lg: 81px;
}

/* ==========================================================================
   1. 重置与中文排版基线
   ========================================================================== */
*, *::before, *::after { box-sizing: border-box; }
[hidden] { display: none !important; }

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: 96px;
}

body {
  margin: 0;
  background-color: var(--color-surface);
  color: var(--color-ink);
  font-family: var(--font-body);
  font-size: var(--text-base);
  font-weight: var(--weight-body);
  line-height: var(--leading-body);
  letter-spacing: 0.012em;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

h1, h2, h3, h4, h5, h6 {
  margin: 0;
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
  color: var(--color-ink);
  text-wrap: balance;
}

p { margin: 0; }
ul, ol { margin: 0; padding: 0; }
li { list-style: none; }
img, svg, video, canvas { display: block; max-width: 100%; }
button { font: inherit; color: inherit; }
a { color: var(--color-primary); text-decoration: none; }
a, button { -webkit-tap-highlight-color: transparent; }

:focus-visible {
  outline: 2px solid var(--color-focus);
  outline-offset: 2px;
  border-radius: var(--radius-sm);
}

.mono {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  letter-spacing: -0.01em;
}

/* ==========================================================================
   2. 布局骨架
   ========================================================================== */
.container {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.section { padding-block: var(--section-y); }
.section--tight { padding-block: var(--space-6); }
.section--loose { padding-block: var(--section-y-lg); }

.grid-12 {
  display: grid;
  grid-template-columns: repeat(12, minmax(0, 1fr));
  gap: var(--gutter);
}
.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; }

.prose {
  max-width: var(--measure);
  font-size: var(--text-base);
  line-height: var(--leading-body);
  color: var(--color-ink);
}
.prose p { margin-bottom: var(--space-3); }
.prose h2 { font-size: var(--text-2xl); margin: var(--space-6) 0 var(--space-2); }
.prose h3 { font-size: var(--text-xl); margin: var(--space-4) 0 var(--space-2); }
.prose ul, .prose ol { padding-left: 1.25em; margin-bottom: var(--space-3); }
.prose li { list-style: disc; margin-bottom: var(--space-1); }
.prose li::marker { color: var(--color-primary); }
.prose strong { font-weight: 600; color: var(--color-ink); }

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
  color: var(--color-ink-muted);
  margin-bottom: var(--space-2);
}

.source-note {
  display: block;
  text-align: right;
  margin-top: var(--space-3);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  line-height: 1.5;
  letter-spacing: 0;
  color: var(--color-ink-muted);
}

.skip-link {
  position: fixed;
  top: -80px;
  left: var(--space-3);
  z-index: 400;
  padding: 11px 18px;
  background: var(--color-primary);
  color: var(--color-primary-ink);
  border-radius: var(--radius-sm);
  font-size: var(--text-sm);
  font-weight: 600;
  box-shadow: var(--shadow-2);
  transition: top 0.2s ease;
}
.skip-link:focus { top: var(--space-2); }

/* ==========================================================================
   3. 页面头部：固定导航作为页面上边框
   ========================================================================== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 120;
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-bottom: var(--border-thin) solid var(--color-contrast-line);
}

.header-inner {
  position: relative;
  display: flex;
  align-items: center;
  gap: var(--space-4);
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding: 0 var(--gutter);
  min-height: 68px;
}

/* --- 品牌锁定 --- */
.brand {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  flex: 0 0 auto;
  color: inherit;
  text-decoration: none;
}
.brand-mark {
  display: grid;
  place-items: center;
  width: 36px;
  height: 36px;
  padding: 3px;
  border: var(--border-thin) solid color-mix(in srgb, currentColor 30%, transparent);
  border-radius: var(--radius-sm);
  color: inherit;
  transition: border-color 0.18s ease, color 0.18s ease;
}
.brand-mark svg { width: 100%; height: 100%; }
.brand-text { display: block; min-width: 0; }
.brand-name {
  display: block;
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: 800;
  line-height: 1.1;
  letter-spacing: 0.02em;
  color: currentColor;
}
.brand-tag {
  display: block;
  margin-top: 3px;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.03em;
  color: color-mix(in srgb, currentColor 62%, transparent);
}
.brand:hover .brand-mark { border-color: var(--color-primary); color: var(--color-primary); }

/* --- 中部六个栏目 --- */
.primary-nav { margin-inline: auto; }
.nav-list {
  display: flex;
  align-items: center;
  gap: var(--space-1);
}
.nav-link {
  display: block;
  padding: 8px 12px;
  border: var(--border-thin) solid transparent;
  border-radius: var(--radius-sm);
  font-size: var(--text-sm);
  font-weight: 500;
  line-height: 1.4;
  color: color-mix(in srgb, var(--color-contrast-ink) 78%, transparent);
  white-space: nowrap;
  transition: color 0.18s ease, background-color 0.18s ease, border-color 0.18s ease;
}
.nav-link:hover {
  color: var(--color-contrast-ink);
  border-color: var(--color-contrast-line);
  background: color-mix(in srgb, var(--color-contrast-ink) 9%, transparent);
}
.nav-link[aria-current="page"] {
  background: var(--color-primary);
  border-color: var(--color-primary);
  color: var(--color-primary-ink);
  font-weight: 600;
}

/* --- 右侧元信息 --- */
.header-meta {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  flex: 0 0 auto;
}
.update-badge {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  padding: 6px 12px;
  border: var(--border-thin) solid var(--color-contrast-line);
  border-radius: var(--radius-pill);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.02em;
  color: color-mix(in srgb, var(--color-contrast-ink) 72%, transparent);
  white-space: nowrap;
}
.update-badge time { font-variant-numeric: tabular-nums; }
.update-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--color-contrast-accent);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--color-contrast-accent) 22%, transparent);
}
.update-note { color: var(--color-contrast-ink); }

.ghost-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 13px;
  background: transparent;
  border: var(--border-thin) solid var(--color-contrast-line);
  border-radius: var(--radius-pill);
  color: var(--color-contrast-ink);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.02em;
  cursor: pointer;
  white-space: nowrap;
  transition: background-color 0.18s ease, border-color 0.18s ease, color 0.18s ease;
}
.ghost-btn:hover {
  border-color: var(--color-primary);
  background: color-mix(in srgb, var(--color-primary) 24%, transparent);
}
.ghost-btn[aria-expanded="true"] {
  background: var(--color-primary);
  border-color: var(--color-primary);
  color: var(--color-primary-ink);
}

.nav-toggle {
  display: none;
  align-items: center;
  gap: 8px;
  padding: 8px 13px;
  background: transparent;
  border: var(--border-thin) solid var(--color-contrast-line);
  border-radius: var(--radius-sm);
  color: var(--color-contrast-ink);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  cursor: pointer;
  transition: border-color 0.18s ease;
}
.nav-toggle:hover { border-color: var(--color-primary); }
.nav-toggle-bars {
  position: relative;
  display: block;
  width: 16px;
  height: 12px;
}
.nav-toggle-bars::before,
.nav-toggle-bars::after {
  content: "";
  position: absolute;
  left: 0;
  width: 16px;
  height: 1.5px;
  background: currentColor;
  transition: transform 0.2s ease;
}
.nav-toggle-bars::before { top: 2px; }
.nav-toggle-bars::after { bottom: 2px; }
.nav-toggle[aria-expanded="true"] .nav-toggle-bars::before { transform: translateY(4px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] .nav-toggle-bars::after { transform: translateY(-4px) rotate(-45deg); }

/* --- 快捷筛选抽屉 --- */
.quick-filter {
  background: color-mix(in srgb, var(--color-contrast-surface) 90%, var(--color-primary) 10%);
  border-top: var(--border-thin) solid var(--color-contrast-line);
}
.quick-filter-inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-3);
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding: var(--space-3) var(--gutter);
}
.filter-label {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
  color: color-mix(in srgb, var(--color-contrast-ink) 60%, transparent);
}
.filter-chips { display: flex; flex-wrap: wrap; gap: 8px; }
.filter-chip {
  padding: 5px 12px;
  background: transparent;
  border: var(--border-thin) solid var(--color-contrast-line);
  border-radius: var(--radius-pill);
  color: color-mix(in srgb, var(--color-contrast-ink) 82%, transparent);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.02em;
  cursor: pointer;
  transition: background-color 0.18s ease, border-color 0.18s ease, color 0.18s ease;
}
.filter-chip:hover { border-color: var(--color-primary); color: var(--color-contrast-ink); }
.filter-chip[aria-pressed="true"] {
  background: var(--color-primary);
  border-color: var(--color-primary);
  color: var(--color-primary-ink);
}
.filter-link {
  margin-left: auto;
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--color-contrast-ink);
  border-bottom: var(--border-thin) solid var(--color-contrast-accent);
  padding-bottom: 2px;
}
.filter-link:hover { color: var(--color-contrast-accent); }

/* --- 滚动进度条 --- */
.header-progress {
  position: absolute;
  left: 0;
  bottom: 0;
  display: block;
  width: 100%;
  height: 2px;
  background: var(--color-contrast-accent);
  transform: scaleX(0);
  transform-origin: 0 50%;
  pointer-events: none;
  will-change: transform;
}

/* ==========================================================================
   4. 通用组件
   ========================================================================== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 21px;
  border: var(--border-thin) solid transparent;
  border-radius: var(--radius-md);
  font-family: var(--font-heading);
  font-size: var(--text-sm);
  font-weight: 600;
  letter-spacing: 0.01em;
  text-decoration: none;
  cursor: pointer;
  transition: transform 0.18s ease, background-color 0.18s ease, border-color 0.18s ease, color 0.18s ease;
}
.btn:hover { transform: translateY(-2px); }
.btn--primary { background: var(--color-primary); color: var(--color-primary-ink); }
.btn--primary:hover { background: color-mix(in srgb, var(--color-primary) 84%, #000); }
.btn--ghost {
  background: transparent;
  border-color: var(--color-line);
  color: var(--color-ink);
}
.btn--ghost:hover { border-color: var(--color-primary); color: var(--color-primary); }
.btn--accent { background: var(--color-accent); color: var(--color-accent-ink); }
.btn--accent:hover { background: color-mix(in srgb, var(--color-accent) 86%, #000); }

.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  margin-bottom: var(--space-3);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.02em;
  color: var(--color-ink-muted);
}
.breadcrumb li { display: inline-flex; align-items: center; gap: 8px; }
.breadcrumb li + li::before {
  content: "/";
  color: var(--color-line);
}
.breadcrumb a { color: var(--color-ink-soft); }
.breadcrumb a:hover { color: var(--color-primary); }
.breadcrumb [aria-current="page"] { color: var(--color-ink); }

.panel {
  background: var(--color-surface);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-1);
  padding: var(--space-4);
}
.panel--alt { background: var(--color-surface-alt); }
.panel--flat { box-shadow: none; }
.panel--dark {
  background: var(--color-contrast-surface);
  border-color: var(--color-contrast-line);
  color: var(--color-contrast-ink);
}
.panel--dark h2,
.panel--dark h3,
.panel--dark h4 { color: var(--color-contrast-ink); }
.panel--dark .metric-value { color: var(--color-contrast-ink); }
.panel--dark .metric-label,
.panel--dark .source-note,
.panel--dark .eyebrow {
  color: color-mix(in srgb, var(--color-contrast-ink) 64%, transparent);
}
.panel--dark .tag {
  background: color-mix(in srgb, var(--color-contrast-ink) 14%, transparent);
  color: var(--color-contrast-ink);
}
.panel--dark .tag--accent {
  background: color-mix(in srgb, var(--color-contrast-accent) 26%, transparent);
  color: var(--color-contrast-ink);
}

.metric {
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
}
.metric-value {
  display: flex;
  align-items: baseline;
  gap: 7px;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: var(--text-3xl);
  font-weight: 700;
  line-height: 1.04;
  letter-spacing: -0.025em;
  color: var(--color-ink);
}
.metric--lg .metric-value { font-size: var(--text-figure); }
.metric-unit {
  font-family: var(--font-body);
  font-size: var(--text-sm);
  font-weight: 500;
  letter-spacing: 0;
  color: var(--color-ink-muted);
}
.metric-label {
  font-size: var(--text-sm);
  line-height: 1.5;
  color: var(--color-ink-soft);
}
.metric--accent .metric-value { color: var(--color-accent); }

.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 11px;
  border-radius: var(--radius-pill);
  background: var(--color-primary-soft);
  color: var(--color-primary);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.02em;
  white-space: nowrap;
}
.tag--accent { background: var(--color-highlight); color: var(--color-accent); }
.tag--neutral { background: var(--color-surface-deep); color: var(--color-ink-soft); }

.frame {
  position: relative;
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-lg);
  overflow: hidden;
}
.frame--dark {
  background: var(--color-contrast-surface);
  border-color: var(--color-contrast-line);
  color: var(--color-contrast-ink);
}

/* --- 图片容器：去边直角，贴合内容边界 --- */
.media {
  position: relative;
  display: block;
  overflow: hidden;
  border-radius: 0;
  aspect-ratio: 16 / 9;
  background: var(--color-surface-deep);
}
.media > img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 0.4s ease;
}
.media:hover > img { transform: scale(1.02); }
.media--4x3 { aspect-ratio: 4 / 3; }
.media--1x1 { aspect-ratio: 1 / 1; }
.media--3x4 { aspect-ratio: 3 / 4; }
.media--21x9 { aspect-ratio: 21 / 9; }
.media-caption {
  position: absolute;
  inset: auto 0 0 0;
  padding: var(--space-4) var(--space-3) var(--space-3);
  background: var(--overlay-scrim);
  color: var(--color-contrast-ink);
  font-size: var(--text-sm);
  line-height: 1.5;
}
.media-caption .mono { color: var(--color-contrast-ink); }

/* --- 可展开内容组 --- */
.disclosure {
  background: var(--color-surface-alt);
  border-radius: var(--radius-md);
}
.disclosure + .disclosure { margin-top: var(--space-1); }
.disclosure-trigger {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
  width: 100%;
  padding: var(--space-3) var(--space-4);
  background: transparent;
  border: 0;
  text-align: left;
  cursor: pointer;
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: 600;
  line-height: 1.35;
  color: var(--color-ink);
  transition: color 0.18s ease;
}
.disclosure-trigger:hover { color: var(--color-primary); }
.disclosure-icon {
  position: relative;
  flex: 0 0 auto;
  width: 14px;
  height: 14px;
}
.disclosure-icon::before,
.disclosure-icon::after {
  content: "";
  position: absolute;
  background: var(--color-primary);
  transition: transform 0.22s ease, background-color 0.22s ease;
}
.disclosure-icon::before { left: 0; top: 6px; width: 14px; height: 2px; }
.disclosure-icon::after { left: 6px; top: 0; width: 2px; height: 14px; }
.disclosure-trigger[aria-expanded="true"] .disclosure-icon::after { transform: scaleY(0); }
.disclosure-trigger[aria-expanded="true"] .disclosure-icon::before { background: var(--color-accent); }
.disclosure-panel {
  overflow: hidden;
  padding: 0 var(--space-4);
  transition: height 0.26s ease, opacity 0.26s ease;
}
.disclosure-panel > .disclosure-body { padding-bottom: var(--space-4); }

/* ==========================================================================
   5. 页脚：卡片式面板
   ========================================================================== */
.site-footer {
  margin-top: var(--section-y-lg);
  padding-block: var(--space-8) var(--space-6);
  background: var(--color-surface-alt);
}

.footer-inner {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.footer-lead {
  display: flex;
  flex-wrap: wrap;
  align-items: flex-start;
  justify-content: space-between;
  gap: var(--space-4);
  margin-bottom: var(--space-6);
}
.brand--footer { color: var(--color-ink); }
.footer-note {
  max-width: 46ch;
  font-size: var(--text-sm);
  line-height: 1.7;
  color: var(--color-ink-soft);
}

.footer-panels {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: var(--space-4);
}
.footer-panel {
  background: var(--color-surface);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-1);
  padding: var(--space-3) var(--space-4) var(--space-4);
}
.footer-panel-title {
  margin-bottom: var(--space-2);
  padding-bottom: var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-weight: 600;
  letter-spacing: 0.16em;
  color: var(--color-ink-muted);
  border-bottom: var(--border-thin) solid var(--color-surface-deep);
}
.footer-list {
  display: grid;
  gap: 9px;
}
.footer-list li {
  font-size: var(--text-sm);
  line-height: 1.6;
  color: var(--color-ink-soft);
}
.footer-list a {
  color: var(--color-ink);
  border-bottom: var(--border-thin) solid transparent;
  transition: color 0.18s ease, border-color 0.18s ease;
}
.footer-list a:hover {
  color: var(--color-primary);
  border-bottom-color: var(--color-primary);
}
.footer-list .mono { color: var(--color-ink); }

.footer-base {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
  margin-top: var(--space-6);
  padding-top: var(--space-4);
  font-size: var(--text-xs);
  line-height: 1.7;
  color: var(--color-ink-muted);
}
.footer-base p:first-child { font-family: var(--font-mono); letter-spacing: 0.02em; }

.to-top {
  position: fixed;
  right: var(--space-4);
  bottom: var(--space-4);
  z-index: 110;
  display: grid;
  place-items: center;
  width: 46px;
  height: 46px;
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-md);
  background: var(--color-surface);
  color: var(--color-primary);
  font-size: var(--text-lg);
  line-height: 1;
  cursor: pointer;
  box-shadow: var(--shadow-2);
  opacity: 0;
  visibility: hidden;
  transform: translateY(8px);
  transition: opacity 0.2s ease, transform 0.2s ease, visibility 0.2s ease, border-color 0.18s ease;
}
.to-top[data-visible="true"] {
  opacity: 1;
  visibility: visible;
  transform: none;
}
.to-top:hover { border-color: var(--color-primary); }

/* ==========================================================================
   6. 响应式
   ========================================================================== */
@media (max-width: 1180px) {
  .nav-link { padding: 7px 9px; font-size: var(--text-xs); }
  .brand-tag { display: none; }
  .update-badge { padding: 5px 10px; }
}

@media (max-width: 1024px) {
  .col-3, .col-4, .col-5 { grid-column: span 6; }
  .col-7, .col-8 { grid-column: span 12; }
  .footer-panels { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (max-width: 900px) {
  html { scroll-padding-top: 76px; }

  .header-inner { min-height: 62px; gap: var(--space-2); }
  .nav-toggle { display: inline-flex; }

  .primary-nav {
    position: absolute;
    left: 0;
    right: 0;
    top: 100%;
    display: none;
    margin: 0;
    padding: var(--space-2) var(--gutter) var(--space-3);
    background: var(--color-contrast-surface);
    border-bottom: var(--border-thin) solid var(--color-contrast-line);
    box-shadow: var(--shadow-2);
    max-height: calc(100vh - 62px);
    overflow-y: auto;
  }
  .site-header[data-open="true"] .primary-nav { display: block; }
  .nav-list { flex-direction: column; align-items: stretch; gap: 2px; }
  .nav-link { padding: 12px; font-size: var(--text-base); border-radius: var(--radius-sm); }

  .filter-toggle { display: none; }
  .quick-filter-inner { flex-direction: column; align-items: flex-start; }
  .filter-link { margin-left: 0; }

  .panel { padding: var(--space-3); }
  .disclosure-trigger { font-size: var(--text-base); padding: var(--space-3); }
  .disclosure-panel { padding-inline: var(--space-3); }
}

@media (max-width: 760px) {
  .grid-12 { grid-template-columns: 1fr; gap: var(--space-3); }
  .col-3, .col-4, .col-5, .col-6, .col-7, .col-8, .col-12 { grid-column: span 1; }
}

@media (max-width: 620px) {
  .footer-panels { grid-template-columns: 1fr; }
  .footer-lead { flex-direction: column; }
  .footer-base { flex-direction: column; align-items: flex-start; }
  .update-badge { display: none; }
  .brand-name { font-size: var(--text-base); }
  .to-top { right: var(--space-3); bottom: var(--space-3); width: 42px; height: 42px; }
}

/* ==========================================================================
   7. 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;
    scroll-behavior: auto !important;
  }
  .btn:hover { transform: none; }
  .media:hover > img { transform: none; }
}

@media print {
  .site-header, .site-footer, .to-top, .skip-link { display: none; }
}