/* ============================================================
   B体育在线 · 共享样式表 /assets/site.css
   手册式条款：编号章节 · 要点框 · 细实线 · 深底插页
   ============================================================ */

:root {
  --color-surface: #fbfbfb;
  --color-surface-alt: #f2f2f2;
  --color-surface-deep: #e5e6e6;
  --color-ink: #45484f;
  --color-ink-soft: #696e77;
  --color-ink-muted: #797d86;
  --color-line: #dadbdc;
  --color-primary: #3966c6;
  --color-primary-ink: #ffffff;
  --color-primary-soft: #e0e6f4;
  --color-accent: #e60f6c;
  --color-accent-ink: #ffffff;
  --color-highlight: #f7d1e1;
  --color-focus: #de0362;
  --color-contrast-surface: #0e1118;
  --color-contrast-ink: #e4e5e7;
  --color-contrast-line: #3d4046;
  --color-contrast-accent: #ef1574;
  --overlay-scrim: linear-gradient(180deg, rgba(14, 17, 24, 0.35) 0%, rgba(14, 17, 24, 0.72) 55%, rgba(14, 17, 24, 0.92) 100%);
  --font-heading: "Songti SC", "Source Han Serif SC", "Noto Serif SC", SimSun, serif;
  --font-body: "PingFang SC", "Microsoft YaHei", "Source Han Sans SC", sans-serif;
  --font-mono: ui-monospace, Menlo, Consolas, monospace;
  --text-xs: 11.4px;
  --text-sm: 14.3px;
  --text-base: 16px;
  --text-lg: 20.0px;
  --text-xl: 25.0px;
  --text-2xl: 31.2px;
  --text-3xl: 39.1px;
  --text-4xl: 48.8px;
  --text-display: clamp(34px, 4.3vw, 55px);
  --text-figure: clamp(28px, 3.1vw, 40px);
  --weight-heading: 676;
  --weight-body: 400;
  --leading-body: 1.82;
  --leading-heading: 1.22;
  --tracking-heading: -0.001em;
  --radius-sm: 0px;
  --radius-md: 1px;
  --radius-lg: 2px;
  --radius-pill: 2px;
  --border-thin: 1px;
  --border-thick: 1px;
  --shadow-1: none;
  --shadow-2: none;
  --space-1: 8px;
  --space-2: 16px;
  --space-3: 24px;
  --space-4: 32px;
  --space-6: 48px;
  --space-8: 64px;
  --container: 1040px;
  --measure: 70ch;
  --gutter: 32px;
  --section-y: 74px;
  --section-y-lg: 104px;
}

/* ---------- 01 Reset ---------- */
*,
*::before,
*::after { box-sizing: border-box; }

html {
  -webkit-text-size-adjust: 100%;
  text-size-adjust: 100%;
  scroll-padding-top: calc(var(--header-h, 64px) + var(--space-2));
}

@media (prefers-reduced-motion: no-preference) {
  html { scroll-behavior: smooth; }
}

body {
  margin: 0;
  padding-top: var(--header-h, 64px);
  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);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

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

::selection {
  background-color: var(--color-primary-soft);
  color: var(--color-ink);
}

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

/* ---------- 02 中文排版 ---------- */
h1, h2, h3, h4, h5, h6 {
  margin: 0 0 var(--space-2);
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
  color: var(--color-ink);
}

h1 { font-size: var(--text-2xl); }
h2 { font-size: var(--text-xl); }
h3 { font-size: var(--text-lg); }
h4 {
  font-family: var(--font-body);
  font-size: var(--text-base);
  font-weight: 600;
}

p { margin: 0 0 var(--space-2); }
p:last-child { margin-bottom: 0; }

a {
  color: var(--color-primary);
  text-decoration: none;
  text-underline-offset: 3px;
  transition: color 140ms ease-out, border-color 140ms ease-out, background-color 140ms ease-out;
}

a:hover { text-decoration: underline; }

ul, ol {
  margin: 0 0 var(--space-2);
  padding-left: 1.4em;
}

li { margin-bottom: var(--space-1); }
li:last-child { margin-bottom: 0; }

strong { font-weight: 600; }

hr {
  border: 0;
  border-top: var(--border-thin) solid var(--color-line);
  margin: var(--space-4) 0;
}

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

.num,
.mono {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-feature-settings: "tnum" 1;
}

.figure {
  display: block;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: var(--text-figure);
  line-height: var(--leading-heading);
  letter-spacing: -0.02em;
  color: var(--color-ink);
}

.visually-hidden {
  position: absolute !important;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
  border: 0;
}

/* ---------- 03 布局容器 ---------- */
.container {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--space-3);
}

.wrap {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--space-3);
}

.section { padding-block: var(--section-y); }
.section--lg { padding-block: var(--section-y-lg); }
.section--tight { padding-block: var(--space-4); }
.section--alt {
  background-color: var(--color-surface-alt);
  border-block: var(--border-thin) solid var(--color-line);
}
.section--deep {
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-block: var(--border-thin) solid var(--color-contrast-line);
}
.section--deep h1,
.section--deep h2,
.section--deep h3,
.section--deep h4 { color: var(--color-contrast-ink); }
.section--deep p { color: color-mix(in srgb, var(--color-contrast-ink) 82%, transparent); }
.section--deep a { color: var(--color-contrast-accent); }
.section--deep .rule { border-top-color: var(--color-contrast-line); }
.section--deep .figure { color: var(--color-contrast-ink); }

.rule {
  border: 0;
  border-top: var(--border-thin) solid var(--color-line);
  margin: 0;
}
.rule--deep { border-top-color: var(--color-contrast-line); }

.stack > * + * { margin-top: var(--space-3); }
.stack--tight > * + * { margin-top: var(--space-2); }
.stack--loose > * + * { margin-top: var(--space-4); }

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

.grid { display: grid; gap: var(--gutter); }
.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)); }
.grid--12 { grid-template-columns: repeat(12, minmax(0, 1fr)); }
.grid--tight { gap: var(--space-2); }

.prose { max-width: var(--measure); }
.prose > p { margin-bottom: var(--space-3); }
.prose > p:last-child { margin-bottom: 0; }
.prose ul,
.prose ol { margin-bottom: var(--space-3); }

/* ---------- 04 章节头与编号 ---------- */
.sec-head { margin-bottom: var(--space-4); }
.sec-head__num {
  margin: 0 0 var(--space-1);
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: var(--text-sm);
  letter-spacing: 0.08em;
  color: var(--color-primary);
}
.sec-head__title { margin: 0; }
.sec-head__desc {
  margin: var(--space-2) 0 0;
  max-width: var(--measure);
  font-size: var(--text-sm);
  color: var(--color-ink-soft);
}
.section--deep .sec-head__desc { color: color-mix(in srgb, var(--color-contrast-ink) 68%, transparent); }
.section--deep .sec-head__num { color: var(--color-contrast-accent); }

/* ---------- 05 徽标 / 标签 ---------- */
.tag {
  display: inline-flex;
  align-items: center;
  gap: 0.4em;
  padding: 2px var(--space-1);
  border: var(--border-thin) solid var(--color-primary);
  border-radius: var(--radius-sm);
  background-color: var(--color-primary-soft);
  color: var(--color-primary);
  font-family: var(--font-body);
  font-size: var(--text-xs);
  line-height: 1.6;
  letter-spacing: 0.05em;
  white-space: nowrap;
}
.tag--solid {
  background-color: var(--color-primary);
  border-color: var(--color-primary);
  color: var(--color-primary-ink);
}
.tag--line {
  background-color: transparent;
  border-color: var(--color-line);
  color: var(--color-ink-soft);
}
.tag--accent {
  background-color: var(--color-highlight);
  border-color: var(--color-accent);
  color: var(--color-accent);
}
.tag--deep {
  background-color: transparent;
  border-color: var(--color-contrast-line);
  color: var(--color-contrast-ink);
}

/* ---------- 06 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-1);
  padding: 10px var(--space-3);
  border: var(--border-thin) solid var(--color-primary);
  border-radius: var(--radius-sm);
  background-color: transparent;
  color: var(--color-primary);
  font-family: var(--font-body);
  font-size: var(--text-sm);
  line-height: 1.4;
  letter-spacing: 0.02em;
  text-decoration: none;
  cursor: pointer;
  transition: background-color 160ms ease-out, color 160ms ease-out, border-color 160ms ease-out;
}
.btn:hover {
  background-color: var(--color-primary-soft);
  text-decoration: none;
}
.btn--primary {
  background-color: var(--color-primary);
  border-color: var(--color-primary);
  color: var(--color-primary-ink);
}
.btn--primary:hover {
  background-color: color-mix(in srgb, var(--color-primary) 84%, #000);
  color: var(--color-primary-ink);
}
.btn--accent {
  border-color: var(--color-accent);
  color: var(--color-accent);
}
.btn--accent:hover { background-color: var(--color-highlight); }
.btn--ghost {
  border-color: var(--color-line);
  color: var(--color-ink-soft);
}
.btn--ghost:hover { background-color: var(--color-surface-alt); color: var(--color-ink); }

/* ---------- 07 要点框 ---------- */
.note {
  position: relative;
  margin: 0 0 var(--space-3);
  padding: var(--space-3) var(--space-3) var(--space-3) var(--space-4);
  border-left: 4px solid var(--color-primary);
  border-radius: var(--radius-sm);
  background-color: var(--color-surface-deep);
  color: var(--color-ink-soft);
  font-size: var(--text-sm);
}
.note:last-child { margin-bottom: 0; }
.note__title {
  display: block;
  margin: 0 0 var(--space-1);
  font-family: var(--font-body);
  font-size: var(--text-xs);
  font-weight: 600;
  letter-spacing: 0.1em;
  color: var(--color-primary);
}
.note--accent { border-left-color: var(--color-accent); background-color: var(--color-highlight); }
.note--accent .note__title { color: var(--color-accent); }
.note--deep {
  border-left-color: var(--color-contrast-accent);
  background-color: color-mix(in srgb, var(--color-contrast-ink) 8%, transparent);
  color: color-mix(in srgb, var(--color-contrast-ink) 80%, transparent);
}
.note--deep .note__title { color: var(--color-contrast-accent); }

/* ---------- 08 面包屑 ---------- */
.breadcrumb { margin-bottom: var(--space-3); }
.breadcrumb__list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-1);
  margin: 0;
  padding: 0;
  list-style: none;
  font-size: var(--text-xs);
}
.breadcrumb__list li {
  display: flex;
  align-items: center;
  gap: var(--space-1);
  margin: 0;
  color: var(--color-ink-muted);
}
.breadcrumb__list li + li::before {
  content: "/";
  color: var(--color-line);
}
.breadcrumb__list a { color: var(--color-ink-soft); }
.breadcrumb__list a:hover { color: var(--color-primary); }

/* ---------- 09 章节索引 / 目录 ---------- */
.toc {
  border-top: var(--border-thin) solid var(--color-line);
  padding-top: var(--space-2);
}
.toc__title {
  margin: 0 0 var(--space-2);
  font-family: var(--font-body);
  font-size: var(--text-xs);
  font-weight: 600;
  letter-spacing: 0.14em;
  color: var(--color-ink-muted);
}
.toc__list {
  margin: 0;
  padding: 0;
  list-style: none;
}
.toc__item { margin: 0; }
.toc__link {
  display: flex;
  align-items: baseline;
  gap: var(--space-1);
  padding: 6px var(--space-2);
  border-left: 2px solid transparent;
  border-bottom: var(--border-thin) solid var(--color-line);
  font-size: var(--text-sm);
  color: var(--color-ink-soft);
  text-decoration: none;
}
.toc__link:hover {
  background-color: var(--color-surface-alt);
  color: var(--color-ink);
  text-decoration: none;
}
.toc__link[aria-current="true"] {
  background-color: var(--color-primary-soft);
  border-left-color: var(--color-primary);
  color: var(--color-ink);
}
.toc__num {
  flex: none;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: var(--text-xs);
  color: var(--color-primary);
}
.toc--deep { border-top-color: var(--color-contrast-line); }
.toc--deep .toc__title { color: color-mix(in srgb, var(--color-contrast-ink) 60%, transparent); }
.toc--deep .toc__link {
  color: color-mix(in srgb, var(--color-contrast-ink) 78%, transparent);
  border-bottom-color: var(--color-contrast-line);
}
.toc--deep .toc__link:hover { background-color: color-mix(in srgb, var(--color-contrast-ink) 8%, transparent); color: var(--color-contrast-ink); }
.toc--deep .toc__link[aria-current="true"] {
  background-color: color-mix(in srgb, var(--color-contrast-accent) 18%, transparent);
  border-left-color: var(--color-contrast-accent);
  color: var(--color-contrast-ink);
}
.toc--deep .toc__num { color: var(--color-contrast-accent); }

/* ---------- 10 可展开内容组 ---------- */
.disclosure { border-top: var(--border-thin) solid var(--color-line); }
.disclosure:last-child { border-bottom: var(--border-thin) solid var(--color-line); }
.disclosure__trigger {
  display: flex;
  width: 100%;
  align-items: flex-start;
  justify-content: space-between;
  gap: var(--space-3);
  padding: var(--space-2) 0;
  border: 0;
  background: none;
  text-align: left;
  font-family: var(--font-body);
  font-size: var(--text-base);
  line-height: var(--leading-body);
  color: var(--color-ink);
  cursor: pointer;
}
.disclosure__trigger:hover { color: var(--color-primary); }
.disclosure__trigger[aria-expanded="true"] { color: var(--color-primary); }
.disclosure__label { flex: 1 1 auto; }
.disclosure__meta {
  flex: none;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
}
.disclosure__icon {
  flex: none;
  width: 9px;
  height: 9px;
  margin-top: 0.55em;
  border-right: var(--border-thin) solid currentColor;
  border-bottom: var(--border-thin) solid currentColor;
  transform: rotate(45deg);
  transition: transform 180ms ease-out;
}
.disclosure__trigger[aria-expanded="true"] .disclosure__icon { transform: rotate(225deg); }
.disclosure__panel {
  padding: 0 0 var(--space-3);
  font-size: var(--text-sm);
  color: var(--color-ink-soft);
}
.disclosure__panel[hidden] { display: none; }
.disclosure--deep { border-top-color: var(--color-contrast-line); }
.disclosure--deep:last-child { border-bottom-color: var(--color-contrast-line); }
.disclosure--deep .disclosure__trigger { color: var(--color-contrast-ink); }
.disclosure--deep .disclosure__panel { color: color-mix(in srgb, var(--color-contrast-ink) 72%, transparent); }

/* ---------- 11 表格 ---------- */
.table {
  width: 100%;
  border-collapse: collapse;
  font-size: var(--text-sm);
}
.table caption {
  caption-side: top;
  padding-bottom: var(--space-1);
  text-align: left;
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
}
.table th,
.table td {
  padding: 10px var(--space-2);
  border-bottom: var(--border-thin) solid var(--color-line);
  text-align: left;
  vertical-align: top;
}
.table thead th {
  background-color: var(--color-surface-deep);
  border-bottom: var(--border-thin) solid var(--color-ink-muted);
  font-family: var(--font-body);
  font-size: var(--text-xs);
  font-weight: 600;
  letter-spacing: 0.06em;
  color: var(--color-ink);
  white-space: nowrap;
}
.table tbody tr:hover { background-color: var(--color-surface-alt); }
.table td.num,
.table th.num,
.table .num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
}
.table--deep { color: var(--color-contrast-ink); }
.table--deep th,
.table--deep td { border-bottom-color: var(--color-contrast-line); }
.table--deep thead th {
  background-color: transparent;
  border-bottom-color: var(--color-contrast-ink);
  color: var(--color-contrast-ink);
}
.table--deep tbody tr:hover { background-color: color-mix(in srgb, var(--color-contrast-ink) 8%, transparent); }

/* ---------- 12 图片容器 ---------- */
.media-frame {
  position: relative;
  display: block;
  overflow: hidden;
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-md);
  background-color: var(--color-surface-deep);
}
.media-frame img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}
.media-frame--ratio-16x9 { aspect-ratio: 16 / 9; }
.media-frame--ratio-4x3 { aspect-ratio: 4 / 3; }
.media-frame--ratio-3x4 { aspect-ratio: 3 / 4; }
.media-frame--ratio-1x1 { aspect-ratio: 1 / 1; }
.media-frame--tall { aspect-ratio: 3 / 4; }
.media-frame--duotone img {
  filter: grayscale(100%) contrast(1.06) brightness(0.94);
}
.media-frame--duotone::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background-color: color-mix(in srgb, var(--color-contrast-surface) 56%, transparent);
  mix-blend-mode: multiply;
}
.media-frame--deep { border-color: var(--color-contrast-line); background-color: var(--color-contrast-surface); }
.media-frame__overlay {
  position: absolute;
  inset: auto 0 0 0;
  padding: var(--space-3);
  background: var(--overlay-scrim);
  color: var(--color-contrast-ink);
  font-size: var(--text-sm);
  line-height: var(--leading-body);
}
.media-frame__overlay * { color: inherit; }
.media-frame__caption {
  margin-top: var(--space-1);
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
}

/* ---------- 13 首屏叠加辅助 ---------- */
.hero--under-nav {
  margin-top: calc(-1 * var(--header-h, 64px));
  padding-top: calc(var(--header-h, 64px) + var(--space-6));
}

/* ---------- 14 页头 ---------- */
.skip-link {
  position: fixed;
  top: -100px;
  left: var(--space-2);
  z-index: 400;
  display: inline-block;
  padding: var(--space-2) var(--space-3);
  border-radius: var(--radius-sm);
  background-color: var(--color-primary);
  color: var(--color-primary-ink);
  font-size: var(--text-sm);
  text-decoration: none;
  transition: top 160ms ease-out;
}
.skip-link:focus {
  top: var(--space-2);
  color: var(--color-primary-ink);
  text-decoration: none;
}

.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 300;
  background-color: var(--color-surface);
  border-bottom: var(--border-thin) solid var(--color-line);
  transition: background-color 200ms ease, border-color 200ms ease;
}

.header-rail {
  background-color: var(--color-surface-alt);
  border-bottom: var(--border-thin) solid var(--color-line);
  transition: background-color 200ms ease, border-color 200ms ease;
}
.header-rail__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-2);
  min-height: 34px;
  padding-block: 5px;
}
.header-rail__note {
  display: flex;
  align-items: center;
  gap: var(--space-1);
  margin: 0;
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
}
.header-rail__links {
  display: flex;
  align-items: center;
  gap: var(--space-3);
}
.header-rail__link {
  font-size: var(--text-xs);
  letter-spacing: 0.04em;
  color: var(--color-ink-soft);
}
.header-rail__link:hover { color: var(--color-primary); text-decoration: none; }

.header-main { position: relative; }
.header-main__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  min-height: 64px;
}

.brand {
  display: flex;
  align-items: baseline;
  gap: var(--space-2);
  flex: none;
  color: var(--color-ink);
  text-decoration: none;
}
.brand:hover { text-decoration: none; }
.brand__mark {
  font-family: var(--font-heading);
  font-size: var(--text-xl);
  font-weight: var(--weight-heading);
  line-height: 1;
  letter-spacing: 0.01em;
  color: var(--color-ink);
}
.brand__meta {
  display: flex;
  flex-direction: column;
  gap: 1px;
}
.brand__full {
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: var(--color-ink-soft);
  line-height: 1.3;
}
.brand__tagline {
  font-size: var(--text-xs);
  letter-spacing: 0.04em;
  color: var(--color-ink-muted);
  line-height: 1.3;
}

.nav-toggle {
  display: none;
  align-items: center;
  gap: var(--space-1);
  padding: 8px 10px;
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-sm);
  background: transparent;
  color: var(--color-ink);
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  cursor: pointer;
}
.nav-toggle:hover { border-color: var(--color-primary); color: var(--color-primary); }
.nav-toggle__bars {
  display: inline-flex;
  flex-direction: column;
  justify-content: space-between;
  width: 14px;
  height: 9px;
}
.nav-toggle__bars span {
  display: block;
  height: 1px;
  background-color: currentColor;
}
.nav-toggle[aria-expanded="true"] {
  border-color: var(--color-primary);
  color: var(--color-primary);
}

.site-nav {
  display: flex;
  flex: 1 1 auto;
  justify-content: flex-end;
}
.site-nav__list {
  display: flex;
  align-items: stretch;
  gap: var(--space-3);
  margin: 0;
  padding: 0;
  list-style: none;
}
.site-nav__item { margin: 0; }
.site-nav__link {
  display: inline-flex;
  align-items: baseline;
  gap: 6px;
  padding-block: 6px;
  border-bottom: 2px solid transparent;
  font-size: var(--text-sm);
  color: var(--color-ink);
  white-space: nowrap;
  text-decoration: none;
  transition: color 160ms ease-out, border-color 160ms ease-out;
}
.site-nav__link:hover {
  color: var(--color-primary);
  text-decoration: none;
}
.site-nav__link[aria-current="page"] {
  border-bottom-color: var(--color-primary);
  color: var(--color-ink);
  font-weight: 600;
}
.site-nav__num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: var(--color-primary);
}

/* 页头叠加态：透明叠在深色首屏上 */
.site-header.is-overlay {
  background-color: transparent;
  border-bottom-color: transparent;
}
.site-header.is-overlay .header-rail {
  background-color: transparent;
  border-bottom-color: color-mix(in srgb, var(--color-contrast-ink) 22%, transparent);
}
.site-header.is-overlay .header-rail__note,
.site-header.is-overlay .header-rail__note-text {
  color: color-mix(in srgb, var(--color-contrast-ink) 74%, transparent);
}
.site-header.is-overlay .header-rail__link {
  color: color-mix(in srgb, var(--color-contrast-ink) 88%, transparent);
}
.site-header.is-overlay .header-rail__link:hover { color: var(--color-contrast-accent); }
.site-header.is-overlay .tag--line {
  border-color: color-mix(in srgb, var(--color-contrast-ink) 38%, transparent);
  color: color-mix(in srgb, var(--color-contrast-ink) 84%, transparent);
}
.site-header.is-overlay .brand__mark,
.site-header.is-overlay .brand__full,
.site-header.is-overlay .brand__tagline,
.site-header.is-overlay .site-nav__link {
  color: var(--color-contrast-ink);
}
.site-header.is-overlay .site-nav__num { color: var(--color-contrast-accent); }
.site-header.is-overlay .site-nav__link[aria-current="page"] {
  border-bottom-color: var(--color-contrast-accent);
}
.site-header.is-overlay .site-nav__link:hover { color: var(--color-contrast-accent); }
.site-header.is-overlay .nav-toggle {
  border-color: var(--color-contrast-line);
  color: var(--color-contrast-ink);
}
.site-header.is-overlay .nav-toggle:hover {
  border-color: var(--color-contrast-accent);
  color: var(--color-contrast-accent);
}

/* ---------- 15 页脚 ---------- */
.site-footer {
  margin-top: var(--section-y-lg);
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-top: var(--border-thin) solid var(--color-contrast-line);
}

.footer-mark {
  display: grid;
  gap: var(--space-3);
  grid-template-columns: minmax(0, 1fr) minmax(0, 34ch);
  align-items: end;
  padding-block: var(--section-y-lg) var(--space-6);
  border-bottom: var(--border-thin) solid var(--color-contrast-line);
}
.footer-mark__word {
  margin: 0;
  font-family: var(--font-heading);
  font-size: var(--text-display);
  font-weight: var(--weight-heading);
  line-height: 1.06;
  letter-spacing: -0.02em;
  color: var(--color-contrast-ink);
}
.footer-mark__note {
  margin: 0;
  font-size: var(--text-sm);
  line-height: var(--leading-body);
  color: color-mix(in srgb, var(--color-contrast-ink) 62%, transparent);
}

.footer-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: var(--space-4) var(--space-3);
  padding-block: var(--space-6);
  border-bottom: var(--border-thin) solid var(--color-contrast-line);
}
.footer-col__title {
  margin: 0 0 var(--space-2);
  font-family: var(--font-body);
  font-size: var(--text-xs);
  font-weight: 600;
  letter-spacing: 0.14em;
  color: var(--color-contrast-accent);
}
.footer-col__list {
  margin: 0;
  padding: 0;
  list-style: none;
}
.footer-col__list li { margin: 0 0 6px; }
.footer-col__list li:last-child { margin-bottom: 0; }
.footer-col__list a {
  font-size: var(--text-sm);
  color: var(--color-contrast-ink);
  text-decoration: none;
}
.footer-col__list a:hover {
  color: var(--color-contrast-accent);
  text-decoration: underline;
  text-underline-offset: 3px;
}
.footer-contact__item {
  margin: 0 0 6px;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: var(--text-sm);
  line-height: 1.6;
  color: var(--color-contrast-ink);
  word-break: break-all;
}
.footer-col__text {
  margin: 0 0 6px;
  font-size: var(--text-xs);
  line-height: 1.7;
  color: color-mix(in srgb, var(--color-contrast-ink) 60%, transparent);
}
.footer-col__text:last-child { margin-bottom: 0; }

.footer-bottom {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--space-2) var(--space-4);
  padding-block: var(--space-4);
}
.footer-bottom__line {
  margin: 0;
  font-size: var(--text-xs);
  line-height: 1.7;
  color: color-mix(in srgb, var(--color-contrast-ink) 52%, transparent);
}
.footer-bottom__line:first-child {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
}

/* ---------- 16 响应式 ---------- */
@media (max-width: 1023px) {
  .footer-mark { grid-template-columns: minmax(0, 1fr); }
  .footer-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .grid--4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .grid--3 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .grid--12 { grid-template-columns: repeat(6, minmax(0, 1fr)); }
}

@media (max-width: 899px) {
  .nav-toggle { display: inline-flex; }

  .site-nav {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    display: none;
    flex: none;
    justify-content: flex-start;
    background-color: var(--color-surface);
    border-top: var(--border-thin) solid var(--color-line);
    border-bottom: var(--border-thin) solid var(--color-line);
  }
  .site-nav[data-open="true"] { display: block; }

  .site-nav__list {
    display: flex;
    flex-wrap: nowrap;
    align-items: center;
    gap: var(--space-3);
    overflow-x: auto;
    padding: var(--space-2) var(--space-3);
    -webkit-overflow-scrolling: touch;
  }
  .site-nav__item { flex: none; }
  .site-nav__link { padding-block: var(--space-1); }
  .site-nav[data-open="true"] .site-nav__link { color: var(--color-ink); }
  .site-nav[data-open="true"] .site-nav__num { color: var(--color-primary); }
  .site-nav[data-open="true"] .site-nav__link[aria-current="page"] {
    border-bottom-color: var(--color-primary);
  }

  .grid--2,
  .grid--3,
  .grid--4 { grid-template-columns: minmax(0, 1fr); }
  .grid--12 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .grid { gap: var(--space-3); }
}

@media (max-width: 599px) {
  .container,
  .wrap { padding-inline: var(--space-2); }
  .section { padding-block: var(--space-6); }
  .section--lg { padding-block: var(--space-8); }
  .header-rail__note { display: none; }
  .last-child { margin-bottom: 0; }
  .brand__full { display: none; }
  .blog, .site { padding-inline: var(--space-2); }
  .footer-grid { grid-template-columns: minmax(0, 1fr); }
  .footer-bottom { flex-direction: column; align-items: flex-start; }
}

/* 断点补充：580–1024 之间的窄平板 */
@media (min-width: 600px) and (max-width: 1023px) {
  .footer-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

/* ---------- 17 动效降级 ---------- */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
    scroll-behavior: auto !important;
  }
}