:root {
  --color-surface: #f8f8f8;
  --color-surface-alt: #efeff0;
  --color-surface-deep: #e2e3e4;
  --color-ink: #424852;
  --color-ink-soft: #666d7b;
  --color-ink-muted: #757c8a;
  --color-line: #d7d8da;
  --color-primary: #3167ce;
  --color-primary-ink: #ffffff;
  --color-primary-soft: #dce4f2;
  --color-accent: #4019e6;
  --color-accent-ink: #ffffff;
  --color-highlight: #d7d0f5;
  --color-focus: #380df2;
  --color-contrast-surface: #0f131b;
  --color-contrast-ink: #e4e5e7;
  --color-contrast-line: #3e4148;
  --color-contrast-accent: #8167ee;
  --overlay-scrim: linear-gradient(180deg, rgba(15, 19, 27, 0.35) 0%, rgba(15, 19, 27, 0.72) 55%, rgba(15, 19, 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: 10.7px;
  --text-sm: 13.4px;
  --text-base: 15px;
  --text-lg: 18.8px;
  --text-xl: 23.4px;
  --text-2xl: 29.3px;
  --text-3xl: 36.6px;
  --text-4xl: 45.8px;
  --text-display: clamp(34px, 6.3vw, 81px);
  --text-figure: clamp(28px, 4.5vw, 58px);
  --weight-heading: 720;
  --weight-body: 400;
  --leading-body: 1.74;
  --leading-heading: 1.16;
  --tracking-heading: 0.029em;
  --radius-sm: 0px;
  --radius-md: 0px;
  --radius-lg: 1px;
  --radius-pill: 1px;
  --border-thin: 1px;
  --border-thick: 1px;
  --shadow-1: none;
  --shadow-2: none;
  --space-1: 7px;
  --space-2: 14px;
  --space-3: 21px;
  --space-4: 28px;
  --space-6: 42px;
  --space-8: 56px;
  --container: 1320px;
  --measure: 73ch;
  --gutter: 28px;
  --section-y: 71px;
  --section-y-lg: 99px;
}

/* ============ reset ============ */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
body, h1, h2, h3, h4, h5, p, ul, ol, li, figure, blockquote, dl, dt, dd { margin: 0; padding: 0; }
ul, ol { list-style: none; }
img, svg, video { display: block; max-width: 100%; height: auto; }
button, input, select, textarea { font: inherit; color: inherit; }
button { background: none; border: 0; cursor: pointer; }
a { color: inherit; text-decoration: none; }
table { border-collapse: collapse; width: 100%; }
[hidden] { display: none !important; }

/* ============ 基础排版 ============ */
body {
  font-family: var(--font-body);
  font-size: var(--text-base);
  font-weight: var(--weight-body);
  line-height: var(--leading-body);
  color: var(--color-ink);
  background-color: var(--color-surface);
  background-image: radial-gradient(color-mix(in srgb, var(--color-line) 72%, transparent) 0.6px, transparent 0.7px);
  background-size: var(--space-4) var(--space-4);
  min-height: 100vh;
  overflow-x: hidden;
}

h1, h2, h3, h4, h5 {
  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-transform: uppercase;
}
h1 { font-size: var(--text-3xl); }
h2 { font-size: var(--text-2xl); }
h3 { font-size: var(--text-xl); }
h4 { font-size: var(--text-lg); }

.prose p, .measure { max-width: var(--measure); }
.prose > * + * { margin-top: var(--space-3); }

.u-mono {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.06em;
  color: var(--color-ink-muted);
}
.u-soft { color: var(--color-ink-soft); }
.u-accent { color: var(--color-accent); }

/* ============ 可达性 ============ */
:focus-visible {
  outline: 2px solid var(--color-focus);
  outline-offset: 2px;
}
#main-content { display: block; scroll-margin-top: 96px; }

.skip-link {
  position: absolute;
  left: var(--space-3);
  top: -140px;
  z-index: 300;
  padding: var(--space-2) var(--space-3);
  background: var(--color-primary);
  color: var(--color-primary-ink);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  border-radius: var(--radius-sm);
  transition: top 0.16s ease;
}
.skip-link:focus { top: var(--space-2); }

/* ============ 布局原语 ============ */
.shell {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--space-4);
}
.section { padding-block: var(--section-y); }
.section--lg { padding-block: var(--section-y-lg); }
.section--tight { padding-block: var(--space-6); }

.grid-12 { display: grid; grid-template-columns: repeat(12, minmax(0, 1fr)); gap: var(--gutter); }
.grid-2 { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: var(--gutter); }
.grid-3 { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: var(--gutter); }
.col-4 { grid-column: span 4; }
.col-6 { grid-column: span 6; }
.col-8 { grid-column: span 8; }

.stack > * + * { margin-top: var(--space-3); }
.stack--loose > * + * { margin-top: var(--space-4); }

.rule-dotted {
  border: 0;
  border-top: 1px dotted var(--color-line);
  margin-block: var(--space-4);
}
.tick-scale {
  height: var(--space-1);
  background-image: repeating-linear-gradient(90deg, var(--color-line) 0 1px, transparent 1px 7px);
}

.block-no {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--color-primary);
}
.block-no::after {
  content: "";
  width: 34px;
  height: 1px;
  background: color-mix(in srgb, var(--color-primary) 45%, transparent);
}

/* ============ 深色分区（唯一反相手段） ============ */
.dark-zone {
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  background-image:
    linear-gradient(color-mix(in srgb, var(--color-contrast-line) 55%, transparent) 1px, transparent 1px),
    linear-gradient(90deg, color-mix(in srgb, var(--color-contrast-line) 55%, transparent) 1px, transparent 1px);
  background-size: var(--space-4) var(--space-4);
}
.dark-zone h1, .dark-zone h2, .dark-zone h3, .dark-zone h4 { color: var(--color-contrast-ink); }
.dark-zone .block-no { color: var(--color-contrast-accent); }
.dark-zone .block-no::after { background: color-mix(in srgb, var(--color-contrast-accent) 55%, transparent); }
.dark-zone .u-mono { color: color-mix(in srgb, var(--color-contrast-ink) 62%, transparent); }

/* ============ 按钮与链接 ============ */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: var(--space-2) var(--space-3);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-sm);
  color: var(--color-ink);
  transition: background-color 0.14s ease, color 0.14s ease, border-color 0.14s ease;
}
.btn:hover { border-color: var(--color-primary); background: var(--color-primary-soft); }
.btn--primary { background: var(--color-primary); border-color: var(--color-primary); color: var(--color-primary-ink); }
.btn--primary:hover { background: color-mix(in srgb, var(--color-primary) 84%, var(--color-contrast-surface)); color: var(--color-primary-ink); }
.btn--accent { background: var(--color-accent); border-color: var(--color-accent); color: var(--color-accent-ink); }
.btn--accent:hover { background: color-mix(in srgb, var(--color-accent) 84%, var(--color-contrast-surface)); }
.btn--ghost { border-style: dotted; color: var(--color-ink-soft); }

.link-u { border-bottom: 1px dotted var(--color-line); transition: border-color 0.14s ease, color 0.14s ease; }
.link-u:hover { color: var(--color-primary); border-bottom-color: var(--color-primary); border-bottom-style: solid; }

/* ============ 徽标 / 标签 ============ */
.tag {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  padding: 2px 7px;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-pill);
  color: var(--color-ink-muted);
  white-space: nowrap;
}
.tag--date { color: var(--color-accent); border-color: color-mix(in srgb, var(--color-accent) 38%, transparent); }
.tag--code { color: var(--color-ink); border-color: color-mix(in srgb, var(--color-accent) 38%, transparent); background: var(--color-highlight); }
.tag--new { color: var(--color-primary-ink); background: var(--color-primary); border-color: var(--color-primary); }

/* ============ 面包屑 ============ */
.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-1);
  padding-block: var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: var(--color-ink-muted);
}
.breadcrumb li { display: inline-flex; align-items: center; gap: var(--space-1); }
.breadcrumb li + li::before { content: "/"; color: var(--color-line); }
.breadcrumb a { border-bottom: 1px dotted var(--color-line); }
.breadcrumb a:hover { color: var(--color-primary); border-bottom-color: var(--color-primary); }
.breadcrumb [aria-current="page"] { color: var(--color-ink); }

/* ============ 数据表格 ============ */
.data-table { font-size: var(--text-sm); }
.data-table caption {
  text-align: left;
  padding-block: var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.12em;
  color: var(--color-ink-muted);
}
.data-table th {
  text-align: left;
  padding: var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  font-weight: 600;
  color: var(--color-primary);
  background: var(--color-primary-soft);
  border-bottom: var(--border-thin) solid var(--color-line);
  white-space: nowrap;
}
.data-table td {
  padding: var(--space-2);
  color: var(--color-ink-soft);
  border-bottom: 1px dotted var(--color-line);
  vertical-align: top;
}
.data-table__field { font-family: var(--font-mono); font-size: var(--text-xs); letter-spacing: 0.06em; color: var(--color-ink-muted); }
.data-table tbody tr { transition: border-color 0.14s ease; }
.data-table tbody tr:hover td:first-child {
  border-left: 3px solid var(--color-primary);
  padding-left: calc(var(--space-2) - 3px);
}
.data-table tbody tr:hover td { color: var(--color-ink); }

/* ============ 卡片 ============ */
.card {
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
  padding: var(--space-3);
  background: var(--color-surface);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-md);
  transition: border-color 0.14s ease, background-color 0.14s ease;
}
.card:hover { border-color: var(--color-primary); background: color-mix(in srgb, var(--color-primary-soft) 38%, var(--color-surface)); }
.card__head { display: flex; align-items: baseline; justify-content: space-between; gap: var(--space-2); }
.card__title { font-size: var(--text-lg); }
.card__body { color: var(--color-ink-soft); font-size: var(--text-sm); }
.card--marked { border-left: 3px solid var(--color-accent); }
.card--quiet { background: var(--color-surface-alt); }

/* ============ 图片容器（供页面阶段放置 CSS/SVG 视觉） ============ */
.media-frame {
  position: relative;
  display: block;
  overflow: hidden;
  background: var(--color-contrast-surface);
  border: var(--border-thin) solid var(--color-contrast-line);
  border-radius: var(--radius-lg);
}
.media-frame > img,
.media-frame > svg { width: 100%; height: auto; display: block; }
.media-frame--ratio { aspect-ratio: 16 / 9; }
.media-frame--ratio-tall { aspect-ratio: 4 / 5; }
.media-frame--soft {
  background: var(--color-surface-deep);
  border-color: var(--color-line);
}
.media-frame__caption {
  position: absolute;
  inset-inline: 0;
  bottom: 0;
  padding: var(--space-2) var(--space-3);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: var(--color-contrast-ink);
  background: var(--overlay-scrim);
}
.media-frame--soft .media-frame__caption { color: var(--color-contrast-ink); }

/* ============ 头部 ============ */
.site-header {
  position: sticky;
  top: 0;
  z-index: 80;
  color: var(--color-ink);
  background: color-mix(in srgb, var(--color-surface) 76%, transparent);
  backdrop-filter: blur(10px) saturate(150%);
  border-bottom: 1px dotted var(--color-line);
  transition: background-color 0.18s ease, border-color 0.18s ease;
}
.site-header[data-scrolled="true"] {
  background: var(--color-surface);
  border-bottom-style: solid;
  border-bottom-color: var(--color-line);
}

.header-inner {
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: var(--space-4);
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding: var(--space-2) var(--space-4);
}

.brand { display: flex; flex-direction: column; gap: 2px; min-width: 0; }
.brand__link { display: flex; flex-direction: column; gap: 1px; }
.brand__mark {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
  color: var(--color-primary);
  text-transform: uppercase;
}
.brand__name {
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-lg);
  letter-spacing: var(--tracking-heading);
  text-transform: uppercase;
  color: var(--color-ink);
}
.brand__fields {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.05em;
  color: var(--color-ink-muted);
  max-width: none;
}

.primary-nav { justify-self: center; min-width: 0; }
.nav-list { display: flex; align-items: center; gap: var(--space-3); }
.nav-item { display: flex; }
.nav-link {
  display: inline-flex;
  align-items: baseline;
  gap: 6px;
  padding: var(--space-1) 2px;
  font-size: var(--text-sm);
  color: var(--color-ink-soft);
  border-bottom: 1px dotted var(--color-line);
  transition: color 0.14s ease, border-color 0.14s ease, background-color 0.14s ease;
}
.nav-link__idx {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: var(--color-primary);
}
.nav-link:hover { color: var(--color-ink); border-bottom-color: var(--color-primary); }
.nav-link[aria-current="page"] {
  color: var(--color-ink);
  border-bottom: 1px solid var(--color-primary);
  background: color-mix(in srgb, var(--color-primary-soft) 62%, transparent);
}

.header-tools { display: flex; align-items: center; gap: var(--space-2); }

.query-strip {
  display: flex;
  align-items: center;
  gap: 2px;
  padding: 3px;
  background: var(--color-surface-deep);
  border: 1px dotted var(--color-line);
  border-radius: var(--radius-sm);
}
.query-strip__label {
  padding-inline: 6px;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.12em;
  color: var(--color-ink-muted);
}
.query-chip {
  padding: 4px 8px;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.04em;
  color: var(--color-ink-soft);
  border: 1px solid transparent;
  border-radius: var(--radius-sm);
  transition: background-color 0.14s ease, color 0.14s ease, border-color 0.14s ease;
}
.query-chip:hover { background: var(--color-primary-soft); color: var(--color-ink); }
.query-chip[aria-pressed="true"] {
  background: var(--color-primary);
  border-color: var(--color-primary);
  color: var(--color-primary-ink);
}
.query-strip__more {
  padding: 4px 6px;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: var(--color-accent);
  border-bottom: 1px dotted currentColor;
}
.query-strip__more:hover { color: var(--color-primary); }

.nav-toggle {
  display: none;
  align-items: center;
  gap: 8px;
  padding: 6px 10px;
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-sm);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  color: var(--color-ink-soft);
  transition: border-color 0.14s ease, color 0.14s ease;
}
.nav-toggle:hover { border-color: var(--color-primary); color: var(--color-ink); }
.nav-toggle__bars { position: relative; display: block; width: 16px; height: 1px; background: currentColor; }
.nav-toggle__bars::before,
.nav-toggle__bars::after {
  content: "";
  position: absolute;
  left: 0;
  width: 16px;
  height: 1px;
  background: currentColor;
}
.nav-toggle__bars::before { top: -5px; }
.nav-toggle__bars::after { top: 5px; }
.nav-toggle[aria-expanded="true"] { border-color: var(--color-primary); background: var(--color-primary-soft); color: var(--color-ink); }

.header-ruler {
  height: var(--space-1);
  border-top: 1px dotted var(--color-line);
  background-image: repeating-linear-gradient(90deg, var(--color-line) 0 1px, transparent 1px 7px);
}

/* ============ 页脚 ============ */
.site-footer {
  margin-top: var(--section-y-lg);
  border-top: var(--border-thin) solid var(--color-line);
  background-color: var(--color-surface-alt);
  background-image: radial-gradient(color-mix(in srgb, var(--color-line) 60%, transparent) 0.6px, transparent 0.7px);
  background-size: var(--space-3) var(--space-3);
}

.footer-tier {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding: var(--space-6) var(--space-4);
}

.footer-tier--index {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: var(--space-4);
  align-items: start;
  border-bottom: 1px dotted var(--color-line);
}
.tier-label {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--color-primary);
  max-width: none;
  padding-top: 2px;
}
.footer-index { display: grid; grid-template-columns: repeat(7, minmax(0, 1fr)); gap: var(--space-2); }
.footer-index a {
  display: flex;
  flex-direction: column;
  gap: 4px;
  padding-top: var(--space-2);
  border-top: var(--border-thin) solid var(--color-line);
  font-size: var(--text-sm);
  color: var(--color-ink-soft);
  transition: color 0.14s ease, border-color 0.14s ease;
}
.footer-index a:hover { color: var(--color-primary); border-top-color: var(--color-primary); }
.footer-index__no {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  color: var(--color-ink-muted);
}
.footer-index a:hover .footer-index__no { color: var(--color-accent); }

.footer-tier--data {
  display: grid;
  grid-template-columns: minmax(0, 1.7fr) minmax(0, 1fr);
  gap: var(--space-6);
  border-bottom: 1px dotted var(--color-line);
}
.footer-groups { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: var(--space-3); }
.footer-group__title {
  display: block;
  margin-bottom: var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.12em;
  color: var(--color-primary);
}
.footer-group ul { display: flex; flex-direction: column; gap: 6px; }
.footer-group a {
  font-size: var(--text-sm);
  color: var(--color-ink-soft);
  border-bottom: 1px dotted transparent;
  transition: color 0.14s ease, border-color 0.14s ease;
}
.footer-group a:hover { color: var(--color-ink); border-bottom-color: var(--color-primary); }

.footer-datum {
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
  padding-left: var(--space-4);
  border-left: 1px dotted var(--color-line);
}
.datum-row {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--space-2);
  padding-bottom: 6px;
  border-bottom: 1px dotted var(--color-line);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: var(--color-ink-muted);
  max-width: none;
}
.datum-row strong {
  font-weight: 600;
  color: var(--color-accent);
  letter-spacing: 0.04em;
}
.footer-datum__note { font-size: var(--text-sm); color: var(--color-ink-soft); max-width: none; }

.footer-tier--legal {
  position: relative;
  max-width: none;
  padding-block: var(--space-4);
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
}
.footer-tier--legal::before {
  content: "";
  position: absolute;
  inset-inline: 0;
  top: 0;
  height: var(--space-1);
  background-image: repeating-linear-gradient(90deg, var(--color-contrast-line) 0 1px, transparent 1px 7px);
}
.footer-legal-inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-1) var(--space-2);
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--space-4);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.05em;
  color: color-mix(in srgb, var(--color-contrast-ink) 78%, transparent);
}
.footer-legal-inner--tail { margin-top: var(--space-2); color: color-mix(in srgb, var(--color-contrast-ink) 58%, transparent); }
.footer-legal__brand { color: var(--color-contrast-accent); letter-spacing: 0.12em; }
.footer-legal-inner a { color: var(--color-contrast-accent); border-bottom: 1px dotted currentColor; transition: color 0.14s ease; }
.footer-legal-inner a:hover { color: var(--color-contrast-ink); }
.footer-legal-inner .sep { color: var(--color-contrast-line); }

/* ============ 平板 ============ */
@media (max-width: 1080px) {
  .query-strip { display: none; }
  .footer-tier--data { grid-template-columns: minmax(0, 1fr); gap: var(--space-4); }
  .footer-datum { padding-left: 0; border-left: 0; border-top: 1px dotted var(--color-line); padding-top: var(--space-3); }
}

/* ============ 移动导航与流式退化 ============ */
@media (max-width: 960px) {
  .header-inner { grid-template-columns: minmax(0, 1fr) auto; gap: var(--space-2); }
  .nav-toggle { display: inline-flex; }
  .primary-nav {
    position: absolute;
    inset-inline: 0;
    top: 100%;
    justify-self: stretch;
    background: var(--color-surface);
    border-top: 1px dotted var(--color-line);
    border-bottom: var(--border-thin) solid var(--color-line);
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.2s ease;
  }
  .primary-nav[data-open="true"] { max-height: 70vh; overflow-y: auto; }
  .nav-list { flex-direction: column; align-items: stretch; gap: 0; padding: var(--space-2) var(--space-4); }
  .nav-item { display: block; }
  .nav-link {
    width: 100%;
    justify-content: flex-start;
    padding: var(--space-2) 0;
    border-bottom: 1px dotted var(--color-line);
    font-size: var(--text-base);
  }
  .nav-link[aria-current="page"] { padding-inline: 6px; }
  .brand__fields { display: none; }

  .grid-12 { grid-template-columns: repeat(6, minmax(0, 1fr)); }
  .col-4, .col-6, .col-8 { grid-column: span 6; }
  .grid-3 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .footer-index { grid-template-columns: repeat(4, minmax(0, 1fr)); }
  .footer-groups { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .footer-tier--index { grid-template-columns: minmax(0, 1fr); gap: var(--space-3); }
}

/* ============ 手机 ============ */
@media (max-width: 640px) {
  .shell, .header-inner, .footer-tier, .footer-legal-inner { padding-inline: var(--space-3); }
  .section { padding-block: var(--space-6); }
  .section--lg { padding-block: var(--section-y); }
  body { background-size: var(--space-3) var(--space-3); }
  .grid-2, .grid-3, .grid-12 { grid-template-columns: minmax(0, 1fr); }
  .col-4, .col-6, .col-8 { grid-column: span 1; }
  .footer-index { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .footer-groups { grid-template-columns: minmax(0, 1fr); }
  .brand__name { font-size: var(--text-base); }
  .data-table--stacked thead { display: none; }
  .data-table--stacked tr { display: block; border-bottom: var(--border-thin) solid var(--color-line); padding-block: var(--space-2); }
  .data-table--stacked td { display: flex; justify-content: space-between; gap: var(--space-2); border-bottom: 0; padding: 4px 0; }
  .data-table--stacked td::before {
    content: attr(data-label);
    font-family: var(--font-mono);
    font-size: var(--text-xs);
    letter-spacing: 0.06em;
    color: var(--color-ink-muted);
  }
  .data-table tbody tr:hover td:first-child { border-left: 0; padding-left: var(--space-2); }
  .media-frame--ratio { aspect-ratio: 4 / 3; }
}

/* ============ 动效降级 ============ */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    transition-duration: 0.001ms !important;
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
  }
}