/* ==========================================================================
   雷竞技会馆 — 共享样式表 /assets/site.css
   复古出版印刷：奶油纸底 / 深棕墨字 / 红橙唯一点色 / 票据双线框 / 刻度收口
   ========================================================================== */

:root {
  --color-surface: #f2f1f0;
  --color-surface-alt: #eae8e7;
  --color-surface-deep: #dedcda;
  --color-ink: #4d423c;
  --color-ink-soft: #74655d;
  --color-ink-muted: #8c7c73;
  --color-line: #d4d2d0;
  --color-primary: #a46847;
  --color-primary-ink: #ffffff;
  --color-primary-soft: #e7ded8;
  --color-accent: #d83a22;
  --color-accent-ink: #ffffff;
  --color-highlight: #edd0cb;
  --color-focus: #cd2c13;
  --color-contrast-surface: #211a17;
  --color-contrast-ink: #e7e5e4;
  --color-contrast-line: #4d4744;
  --color-contrast-accent: #e15742;
  --overlay-scrim: linear-gradient(180deg, rgba(33, 26, 23, 0.35) 0%, rgba(33, 26, 23, 0.72) 55%, rgba(33, 26, 23, 0.92) 100%);
  --font-heading: STZhongsong, "Source Han Serif SC", "Songti SC", SimSun, serif;
  --font-body: "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-mono: ui-monospace, Menlo, Consolas, monospace;
  --text-xs: 11.0px;
  --text-sm: 14.7px;
  --text-base: 17px;
  --text-lg: 22.7px;
  --text-xl: 30.2px;
  --text-2xl: 40.3px;
  --text-3xl: 53.7px;
  --text-4xl: 71.5px;
  --text-display: clamp(48px, 9.8vw, 126px);
  --text-figure: clamp(40px, 7.1vw, 91px);
  --weight-heading: 733;
  --weight-body: 400;
  --leading-body: 1.76;
  --leading-heading: 1.17;
  --tracking-heading: 0.013em;
  --radius-sm: 1px;
  --radius-md: 2px;
  --radius-lg: 2px;
  --radius-pill: 2px;
  --border-thin: 1px;
  --border-thick: 3px;
  --shadow-1: 0 1px 0 rgba(77, 66, 60, 0.12);
  --shadow-2: 0 2px 0 rgba(77, 66, 60, 0.18);
  --space-1: 8px;
  --space-2: 16px;
  --space-3: 24px;
  --space-4: 32px;
  --space-6: 48px;
  --space-8: 64px;
  --container: 1120px;
  --measure: 71ch;
  --gutter: 24px;
  --section-y: 75px;
  --section-y-lg: 105px;
}

/* --------------------------------------------------------------------------
   1. reset 与基础
   -------------------------------------------------------------------------- */
*,
*::before,
*::after { box-sizing: border-box; }

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: 116px;
}

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);
  overflow-x: hidden;
}

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

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

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

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

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

button {
  margin: 0;
  border: 0;
  background: none;
  color: inherit;
  font: inherit;
  cursor: pointer;
}

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

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

.section--contrast :focus-visible,
.site-footer :focus-visible,
.header-top :focus-visible {
  outline-color: var(--color-contrast-accent);
}

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

/* --------------------------------------------------------------------------
   2. 版式辅助
   -------------------------------------------------------------------------- */
.lede {
  max-width: 62ch;
  margin: 0 0 var(--space-3);
  color: var(--color-ink-soft);
  font-size: var(--text-lg);
  line-height: 1.62;
}

.mark {
  padding: 0 3px;
  background-image: linear-gradient(var(--color-highlight), var(--color-highlight));
  background-repeat: no-repeat;
  background-position: 0 86%;
  background-size: 100% 0.5em;
}

.num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-feature-settings: "tnum" 1;
  letter-spacing: 0;
}

.score__value {
  display: block;
  color: var(--color-accent);
  font-family: var(--font-mono);
  font-size: var(--text-figure);
  font-variant-numeric: tabular-nums;
  line-height: 0.94;
}

.score__label {
  display: block;
  margin-top: var(--space-1);
  color: var(--color-ink-muted);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
}

.section--contrast .score__value { color: var(--color-contrast-accent); }
.section--contrast .score__label { color: color-mix(in srgb, var(--color-contrast-ink) 65%, transparent); }

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

.section { padding-block: var(--section-y); }
.section--lg { padding-block: var(--section-y-lg); }

.section--alt { background-color: var(--color-surface-alt); }

.section--deep {
  background-color: var(--color-surface-deep);
  background-image: radial-gradient(color-mix(in srgb, var(--color-ink) 7%, transparent) 1px, transparent 1px);
  background-size: 6px 6px;
}

.section--contrast {
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
}

.section--contrast h1,
.section--contrast h2,
.section--contrast h3,
.section--contrast h4 { color: var(--color-contrast-ink); }

.section--contrast p,
.section--contrast li { color: color-mix(in srgb, var(--color-contrast-ink) 86%, transparent); }

.grid {
  display: grid;
  gap: var(--space-3);
}
.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--sidebar {
  grid-template-columns: minmax(0, 7fr) minmax(0, 3fr);
  gap: var(--space-6);
  align-items: start;
}

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

/* --------------------------------------------------------------------------
   4. 分隔与章节头
   -------------------------------------------------------------------------- */
.rule {
  height: 3px;
  margin: 0;
  border: 0;
  border-top: var(--border-thin) solid var(--color-line);
  border-bottom: var(--border-thin) solid var(--color-line);
}

.rule--accent {
  border-top-color: var(--color-accent);
  border-bottom-color: var(--color-accent);
}

.section--contrast .rule {
  border-top-color: var(--color-contrast-line);
  border-bottom-color: var(--color-contrast-line);
}

.section-head {
  margin-bottom: var(--space-6);
  text-align: center;
}

.section-head__kicker {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  margin: 0 0 var(--space-2);
  color: var(--color-accent);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.18em;
}

.section-head__kicker::before,
.section-head__kicker::after {
  content: "";
  width: 28px;
  height: 3px;
  border-top: var(--border-thin) solid currentColor;
  border-bottom: var(--border-thin) solid currentColor;
}

.section-head__title {
  font-size: var(--text-2xl);
}

.section-head__note {
  max-width: 58ch;
  margin: var(--space-2) auto 0;
  color: var(--color-ink-soft);
  font-size: var(--text-sm);
  line-height: 1.7;
}

.section--contrast .section-head__kicker { color: var(--color-contrast-accent); }
.section--contrast .section-head__note { color: color-mix(in srgb, var(--color-contrast-ink) 74%, transparent); }

/* --------------------------------------------------------------------------
   5. 按钮
   -------------------------------------------------------------------------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-1);
  padding: 11px var(--space-3);
  border: var(--border-thin) solid color-mix(in srgb, var(--color-ink) 26%, transparent);
  border-radius: var(--radius-md);
  background: var(--color-primary);
  color: var(--color-primary-ink);
  font-size: var(--text-sm);
  letter-spacing: 0.08em;
  line-height: 1.2;
  transition: background-color 140ms ease, color 140ms ease, border-color 140ms ease;
}

.btn:hover { background: color-mix(in srgb, var(--color-primary) 82%, var(--color-ink)); }

.btn--accent {
  border-color: color-mix(in srgb, var(--color-ink) 26%, transparent);
  background: var(--color-accent);
  color: var(--color-accent-ink);
}
.btn--accent:hover { background: var(--color-focus); }

.btn--ghost {
  border-color: color-mix(in srgb, currentColor 42%, transparent);
  background: transparent;
  color: inherit;
}
.btn--ghost:hover {
  border-color: var(--color-accent);
  background: color-mix(in srgb, var(--color-accent) 14%, transparent);
  color: var(--color-accent);
}
.section--contrast .btn--ghost:hover,
.site-footer .btn--ghost:hover {
  border-color: var(--color-contrast-accent);
  background: color-mix(in srgb, var(--color-contrast-accent) 18%, transparent);
  color: var(--color-contrast-accent);
}

/* --------------------------------------------------------------------------
   6. 标签 / 说明牌 / 票据 / 目录
   -------------------------------------------------------------------------- */
.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 3px 8px;
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-sm);
  background: var(--color-surface-alt);
  color: var(--color-ink-soft);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.12em;
  line-height: 1.6;
}

.tag--accent {
  border-color: var(--color-accent);
  background: var(--color-accent);
  color: var(--color-accent-ink);
}

.tag--primary {
  border-color: var(--color-primary);
  background: var(--color-primary);
  color: var(--color-primary-ink);
}

.plate {
  padding: var(--space-3);
  border: var(--border-thick) double var(--color-ink);
  border-radius: var(--radius-sm);
  background: var(--color-surface);
}

.plate__title {
  margin: 0 0 var(--space-1);
  color: var(--color-accent);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
}

.plate__body {
  margin: 0;
  color: var(--color-ink-soft);
  font-size: var(--text-sm);
  line-height: 1.72;
}

.section--contrast .plate {
  border-color: var(--color-contrast-line);
  background: color-mix(in srgb, var(--color-contrast-ink) 6%, transparent);
}
.section--contrast .plate__title { color: var(--color-contrast-accent); }
.section--contrast .plate__body { color: color-mix(in srgb, var(--color-contrast-ink) 82%, transparent); }

.ticket {
  padding: var(--space-3);
  border: var(--border-thick) double var(--color-ink);
  border-radius: var(--radius-sm);
  background: var(--color-surface);
}

.ticket__title {
  margin: 0 0 var(--space-1);
  font-family: var(--font-heading);
  font-size: var(--text-lg);
}

.ticket__body {
  margin: 0;
  color: var(--color-ink-soft);
  font-size: var(--text-sm);
}

.ticket__perf {
  height: 0;
  margin: var(--space-3) 0;
  border-top: var(--border-thin) dashed var(--color-line);
}

.toc {
  position: sticky;
  top: 116px;
  padding: var(--space-3);
  border: var(--border-thick) double var(--color-ink);
  border-radius: var(--radius-sm);
  background: var(--color-surface);
}

.toc__title {
  margin: 0 0 var(--space-2);
  color: var(--color-accent);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
}

.toc__list { display: grid; gap: 2px; }

.toc__link {
  display: block;
  padding: 7px 10px;
  border-left: 3px solid transparent;
  color: var(--color-ink-soft);
  font-size: var(--text-sm);
  line-height: 1.5;
  transition: background-color 140ms ease, color 140ms ease, border-color 140ms ease;
}

.toc__link:hover {
  border-left-color: var(--color-primary);
  background: var(--color-primary-soft);
  color: var(--color-ink);
}

.toc__link[aria-current="true"] {
  border-left-color: var(--color-accent);
  background: var(--color-highlight);
  color: var(--color-ink);
}

/* --------------------------------------------------------------------------
   7. 面包屑与正文
   -------------------------------------------------------------------------- */
.breadcrumb {
  padding-block: var(--space-2);
  border-bottom: var(--border-thin) solid var(--color-line);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
}

.breadcrumb__list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  color: var(--color-ink-muted);
}

.breadcrumb__list li { display: inline-flex; align-items: center; gap: 8px; }

.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-accent); }

.prose {
  max-width: var(--measure);
  font-size: var(--text-base);
}

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

.prose h2 {
  margin-top: var(--space-6);
  padding-top: var(--space-2);
  border-top: var(--border-thin) solid var(--color-line);
  font-size: var(--text-xl);
}

.prose h3 {
  margin-top: var(--space-4);
  font-size: var(--text-lg);
}

.prose ul,
.prose ol {
  padding-left: 1.4em;
  list-style: disc;
}

.prose ol { list-style: decimal; }
.prose li { margin-bottom: 6px; }
.prose li::marker { color: var(--color-accent); }

.prose a {
  color: var(--color-accent);
  border-bottom: var(--border-thin) solid currentColor;
}

.prose strong {
  background-image: linear-gradient(var(--color-highlight), var(--color-highlight));
  background-repeat: no-repeat;
  background-position: 0 86%;
  background-size: 100% 0.5em;
}

.prose blockquote {
  margin: var(--space-4) 0;
  padding: var(--space-2) var(--space-3);
  border-left: var(--border-thick) solid var(--color-primary);
  background: var(--color-surface-alt);
  color: var(--color-ink-soft);
}

.prose code {
  padding: 2px 5px;
  border-radius: var(--radius-sm);
  background: var(--color-surface-deep);
  font-family: var(--font-mono);
  font-size: 0.92em;
}

.prose table {
  width: 100%;
  border-collapse: collapse;
  font-size: var(--text-sm);
}

.prose th,
.prose td {
  padding: 10px 12px;
  border-bottom: var(--border-thin) solid var(--color-line);
  text-align: left;
  vertical-align: top;
}

.prose thead th {
  background: var(--color-primary-soft);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
}

.prose tbody tr:nth-child(even) { background: var(--color-surface-alt); }

.section--contrast .prose { color: color-mix(in srgb, var(--color-contrast-ink) 88%, transparent); }
.section--contrast .prose h2,
.section--contrast .prose h3 { color: var(--color-contrast-ink); }
.section--contrast .prose h2 { border-top-color: var(--color-contrast-line); }

/* --------------------------------------------------------------------------
   8. 图片容器
   -------------------------------------------------------------------------- */
.figure-frame {
  margin: 0;
  padding: 10px;
  border: var(--border-thick) double var(--color-ink);
  border-radius: var(--radius-sm);
  background: var(--color-surface-deep);
}

.media {
  position: relative;
  overflow: hidden;
  background: var(--color-surface-alt);
}

.media__img {
  width: 100%;
  height: 100%;
  aspect-ratio: 4 / 3;
  object-fit: cover;
}

.figure-frame--wide .media__img { aspect-ratio: 16 / 9; }
.figure-frame--tall .media__img { aspect-ratio: 3 / 4; }

.media__scrim {
  position: absolute;
  inset: 0;
  background: var(--overlay-scrim);
  pointer-events: none;
}

.media__overlay {
  position: absolute;
  inset: auto 0 0 0;
  margin: 0;
  padding: var(--space-3);
  color: var(--color-contrast-ink);
  font-size: var(--text-sm);
  line-height: 1.6;
}

.figure-frame__cap {
  margin: var(--space-1) 0 0;
  color: var(--color-ink-muted);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
}

.section--contrast .figure-frame {
  border-color: var(--color-contrast-line);
  background: color-mix(in srgb, var(--color-contrast-ink) 5%, transparent);
}

/* --------------------------------------------------------------------------
   9. 通用交互件
   -------------------------------------------------------------------------- */
.scroll-progress {
  position: fixed;
  top: 0;
  left: 0;
  z-index: 200;
  width: 100%;
  height: 3px;
  background: var(--color-accent);
  transform: scaleX(0);
  transform-origin: 0 50%;
  pointer-events: none;
}

.to-top {
  position: fixed;
  right: var(--gutter);
  bottom: var(--space-3);
  z-index: 150;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 10px 14px;
  border: var(--border-thin) solid var(--color-contrast-line);
  border-radius: var(--radius-sm);
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.12em;
  opacity: 0;
  visibility: hidden;
  transition: opacity 200ms ease, visibility 200ms ease;
}

.to-top.is-visible {
  opacity: 1;
  visibility: visible;
}

.to-top:hover {
  border-color: var(--color-contrast-accent);
  color: var(--color-contrast-accent);
}

.reveal {
  opacity: 0;
  transform: translateY(12px);
  transition: opacity 420ms ease, transform 420ms ease;
}

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

/* --------------------------------------------------------------------------
   10. 头部
   -------------------------------------------------------------------------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 120;
  background: var(--color-surface);
}

.skip-link {
  position: absolute;
  left: var(--space-2);
  top: calc(-1 * var(--space-8));
  z-index: 10;
  display: inline-block;
  padding: 10px var(--space-3);
  border: var(--border-thin) solid var(--color-ink);
  border-radius: var(--radius-sm);
  background: var(--color-accent);
  color: var(--color-accent-ink);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.08em;
  transition: top 150ms ease;
}

.skip-link:focus { top: var(--space-2); }

.header-top {
  border-bottom: var(--border-thin) solid var(--color-contrast-line);
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
}

.header-top__inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-1) var(--space-3);
  max-width: var(--container);
  margin-inline: auto;
  padding: var(--space-1) var(--gutter);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  line-height: 1.6;
}

.header-brandline {
  display: flex;
  align-items: center;
  gap: var(--space-1);
  margin: 0;
  color: var(--color-contrast-ink);
}

.header-brandline::before {
  content: "";
  flex: none;
  width: 8px;
  height: 8px;
  background: var(--color-contrast-accent);
}

.header-contact {
  margin: 0;
  color: color-mix(in srgb, var(--color-contrast-ink) 68%, transparent);
}

.header-main {
  position: relative;
  border-bottom: var(--border-thick) double var(--color-ink);
  background: var(--color-surface);
}

.header-main__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
  max-width: var(--container);
  margin-inline: auto;
  padding: var(--space-2) var(--gutter);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  flex: none;
}

.brand__mark {
  display: grid;
  place-items: center;
  flex: none;
  width: 38px;
  height: 38px;
  border: var(--border-thin) solid var(--color-ink);
  border-radius: var(--radius-sm);
  background: var(--color-accent);
  color: var(--color-accent-ink);
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  line-height: 1;
}

.brand__text {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.brand__name {
  color: var(--color-ink);
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  line-height: 1.1;
  letter-spacing: var(--tracking-heading);
}

.brand__sub {
  color: var(--color-ink-muted);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
}

.site-nav__list {
  display: flex;
  align-items: stretch;
  border-right: var(--border-thin) solid var(--color-line);
}

.site-nav__link {
  position: relative;
  display: block;
  padding: 12px var(--space-2) 16px;
  border-left: var(--border-thin) solid var(--color-line);
  color: var(--color-ink);
  font-size: var(--text-sm);
  letter-spacing: 0.06em;
  line-height: 1.3;
  white-space: nowrap;
  transition: background-color 140ms ease, color 140ms ease;
}

.site-nav__link::after {
  content: "";
  position: absolute;
  left: 50%;
  bottom: 6px;
  width: 22px;
  height: 3px;
  background: var(--color-accent);
  transform: translateX(-50%) scaleX(0);
  transform-origin: 50% 50%;
  transition: transform 160ms ease;
}

.site-nav__link:hover {
  background: var(--color-primary-soft);
}

.site-nav__link:hover::after,
.site-nav__link:focus-visible::after,
.site-nav__link[aria-current="page"]::after {
  transform: translateX(-50%) scaleX(1);
}

.site-nav__link[aria-current="page"] {
  background: var(--color-primary-soft);
  color: var(--color-focus);
}

.header-cta {
  display: inline-flex;
  align-items: center;
  flex: none;
  padding: 10px 14px;
  border: var(--border-thin) solid var(--color-ink);
  border-radius: var(--radius-sm);
  background: var(--color-accent);
  color: var(--color-accent-ink);
  font-size: var(--text-xs);
  letter-spacing: 0.12em;
  white-space: nowrap;
  transition: background-color 140ms ease;
}

.header-cta:hover { background: var(--color-focus); }

.nav-toggle {
  display: none;
  align-items: center;
  gap: 8px;
  flex: none;
  padding: 9px 12px;
  border: var(--border-thin) solid var(--color-contrast-line);
  border-radius: var(--radius-sm);
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
}

.nav-toggle[aria-expanded="true"] {
  border-color: var(--color-contrast-accent);
  color: var(--color-contrast-accent);
}

.nav-toggle__bars {
  position: relative;
  display: block;
  width: 16px;
  height: 10px;
  border-top: 2px solid currentColor;
  border-bottom: 2px solid currentColor;
}

.nav-toggle__bars::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  top: 50%;
  height: 2px;
  background: currentColor;
  transform: translateY(-50%);
  transition: opacity 140ms ease;
}

.nav-toggle[aria-expanded="true"] .nav-toggle__bars::after { opacity: 0; }

/* --------------------------------------------------------------------------
   11. 页脚
   -------------------------------------------------------------------------- */
.site-footer {
  border-top: var(--border-thick) double var(--color-contrast-line);
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
}

.footer-ruler {
  height: 14px;
  border-bottom: var(--border-thin) solid var(--color-contrast-line);
  background-image:
    repeating-linear-gradient(90deg, var(--color-contrast-line) 0 1px, transparent 1px 14px),
    repeating-linear-gradient(90deg, var(--color-contrast-accent) 0 2px, transparent 2px 112px);
  background-repeat: repeat-x, repeat-x;
  background-size: 14px 6px, 112px 12px;
  background-position: left bottom, left bottom;
}

.footer-top {
  display: flex;
  flex-wrap: wrap;
  align-items: flex-end;
  justify-content: space-between;
  gap: var(--space-3);
  padding-block: var(--space-6) var(--space-4);
  border-bottom: var(--border-thin) solid var(--color-contrast-line);
}

.footer-brand {
  display: flex;
  align-items: center;
  gap: 12px;
}

.footer-brand__text { display: flex; flex-direction: column; gap: 4px; }

.footer-brand__name {
  margin: 0;
  color: var(--color-contrast-ink);
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  line-height: 1.15;
  letter-spacing: var(--tracking-heading);
}

.footer-brand__line {
  margin: 0;
  color: color-mix(in srgb, var(--color-contrast-ink) 64%, transparent);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
}

.footer-cols {
  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);
  color: var(--color-contrast-accent);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.18em;
}

.footer-col__list {
  display: grid;
  gap: 10px;
}

.footer-col__list a {
  display: inline-block;
  padding-bottom: 2px;
  border-bottom: var(--border-thin) solid transparent;
  color: var(--color-contrast-ink);
  font-size: var(--text-sm);
  line-height: 1.5;
  transition: color 140ms ease, border-color 140ms ease;
}

.footer-col__list a:hover {
  border-bottom-color: var(--color-contrast-accent);
  color: var(--color-contrast-accent);
}

.footer-contact {
  display: grid;
  gap: 6px;
  padding-block: var(--space-3);
  border-bottom: var(--border-thin) solid var(--color-contrast-line);
}

.footer-contact__item {
  margin: 0;
  color: color-mix(in srgb, var(--color-contrast-ink) 86%, transparent);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.04em;
  line-height: 1.6;
}

.footer-contact__note {
  margin: 0;
  color: color-mix(in srgb, var(--color-contrast-ink) 58%, transparent);
  font-size: var(--text-xs);
  line-height: 1.7;
  letter-spacing: 0.04em;
}

.footer-closure {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  margin: 0;
  padding-block: var(--space-6) 0;
  color: var(--color-contrast-ink);
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  line-height: 1.4;
  letter-spacing: var(--tracking-heading);
  text-align: center;
}

.footer-closure span { flex: none; max-width: 46ch; }

.footer-closure::before,
.footer-closure::after {
  content: "";
  flex: 1 1 auto;
  height: 3px;
  border-top: var(--border-thin) solid var(--color-contrast-line);
  border-bottom: var(--border-thin) solid var(--color-contrast-line);
}

.footer-bottom {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-2) var(--space-4);
  padding-block: var(--space-4) var(--space-6);
}

.footer-icp {
  margin: 0;
  color: color-mix(in srgb, var(--color-contrast-ink) 62%, transparent);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
}

.footer-legal {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-3);
}

.footer-legal a {
  color: color-mix(in srgb, var(--color-contrast-ink) 78%, transparent);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
}

.footer-legal a:hover {
  color: var(--color-contrast-accent);
  text-decoration: underline;
}

/* --------------------------------------------------------------------------
   12. 响应式
   -------------------------------------------------------------------------- */
@media (min-width: 900px) {
  .section-head__title { font-size: var(--text-3xl); }
}

@media (max-width: 1023px) {
  .grid--3,
  .grid--4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .grid--sidebar { grid-template-columns: minmax(0, 1fr); gap: var(--space-4); }
  .toc { position: static; }
}

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

  .header-cta { display: none; }

  .header-main__inner { padding-block: var(--space-2); }

  .site-nav {
    display: none;
    position: absolute;
    left: 0;
    right: 0;
    top: 100%;
    max-height: calc(100vh - 120px);
    overflow-y: auto;
    border-top: var(--border-thick) double var(--color-ink);
    border-bottom: var(--border-thick) double var(--color-ink);
    background: var(--color-surface-deep);
  }

  .site-nav[data-open] { display: block; }

  .site-nav__list {
    flex-direction: column;
    border-right: 0;
  }

  .site-nav__link {
    padding: 14px var(--gutter) 16px;
    border-left: 0;
    border-top: var(--border-thin) solid var(--color-line);
    font-size: var(--text-base);
  }

  .site-nav__list li:first-child .site-nav__link { border-top: 0; }

  .site-nav__link::after {
    left: var(--gutter);
    bottom: 12px;
    width: 18px;
    transform: translateX(0) scaleX(0);
    transform-origin: 0 50%;
  }

  .site-nav__link:hover::after,
  .site-nav__link:focus-visible::after,
  .site-nav__link[aria-current="page"]::after {
    transform: translateX(0) scaleX(1);
  }
}

@media (max-width: 767px) {
  :root { --gutter: 18px; }

  html { scroll-padding-top: 96px; }

  .header-contact { display: none; }

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

  .footer-top { align-items: flex-start; }

  .footer-closure {
    flex-direction: column;
    gap: var(--space-2);
    font-size: var(--text-base);
  }

  .footer-closure::before,
  .footer-closure::after { width: 100%; flex: none; }

  .footer-bottom { flex-direction: column; align-items: flex-start; }
}

@media (max-width: 639px) {
  .grid--2,
  .grid--3,
  .grid--4 { grid-template-columns: minmax(0, 1fr); }

  .section { padding-block: calc(var(--section-y) * 0.8); }
  .section--lg { padding-block: calc(var(--section-y-lg) * 0.72); }

  .brand__sub { display: none; }

  .to-top {
    right: var(--space-2);
    bottom: var(--space-2);
  }

  .prose table { display: block; overflow-x: auto; }
}

/* --------------------------------------------------------------------------
   13. 动效偏好
   -------------------------------------------------------------------------- */
@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;
  }

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