/* ==========================================================================
   云体育中心 · 全站共享样式 /assets/site.css
   ========================================================================== */

:root {
  --color-surface: #f8f8f8;
  --color-surface-alt: #efefef;
  --color-surface-deep: #e2e3e3;
  --color-ink: #424a4d;
  --color-ink-soft: #646e72;
  --color-ink-muted: #788387;
  --color-line: #d7d9d9;
  --color-primary: #4f7c8d;
  --color-primary-ink: #ffffff;
  --color-primary-soft: #e0e7e9;
  --color-accent: #1246ed;
  --color-accent-ink: #ffffff;
  --color-highlight: #cfd8f6;
  --color-focus: #063ff9;
  --color-contrast-surface: #1f2528;
  --color-contrast-ink: #e4e6e7;
  --color-contrast-line: #4a4f52;
  --color-contrast-accent: #6385f3;
  --overlay-scrim: linear-gradient(180deg, rgba(31, 37, 40, 0.35) 0%, rgba(31, 37, 40, 0.72) 55%, rgba(31, 37, 40, 0.92) 100%);
  --font-heading: "Helvetica Neue", Arial, "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-body: "Helvetica Neue", Arial, "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  --text-xs: 12.9px;
  --text-sm: 15.5px;
  --text-base: 17px;
  --text-lg: 20.4px;
  --text-xl: 24.5px;
  --text-2xl: 29.4px;
  --text-3xl: 35.3px;
  --text-4xl: 42.3px;
  --text-display: clamp(34px, 5.8vw, 74px);
  --text-figure: clamp(28px, 4.1vw, 53px);
  --weight-heading: 679;
  --weight-body: 400;
  --leading-body: 1.84;
  --leading-heading: 1.24;
  --tracking-heading: 0.003em;
  --radius-sm: 7px;
  --radius-md: 9px;
  --radius-lg: 11px;
  --radius-pill: 999px;
  --border-thin: 1px;
  --border-thick: 1px;
  --shadow-1: 0 6px 18px rgba(66, 74, 77, 0.08);
  --shadow-2: 0 18px 44px rgba(66, 74, 77, 0.14);
  --space-1: 8px;
  --space-2: 16px;
  --space-3: 24px;
  --space-4: 32px;
  --space-6: 48px;
  --space-8: 64px;
  --container: 1160px;
  --measure: 73ch;
  --gutter: 32px;
  --section-y: 94px;
  --section-y-lg: 132px;
}

/* 派生布局变量（非色彩、非字号，仅用于头部高度与断点对齐） */
html {
  --header-h: 60px;
  --header-h-lg: 68px;
  scroll-padding-top: calc(var(--header-h) + var(--space-3));
}
@media (min-width: 900px) {
  html { --header-h: var(--header-h-lg); }
}

/* --------------------------------------------------------------------------
   1. Reset
   -------------------------------------------------------------------------- */
*, *::before, *::after { box-sizing: border-box; }
html {
  -webkit-text-size-adjust: 100%;
  text-size-adjust: 100%;
}
body {
  margin: 0;
  padding-top: var(--header-h);
  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;
}
body.page-hero-underlay { padding-top: 0; }
img, svg, video { max-width: 100%; display: block; height: auto; }
button, input, select, textarea { font: inherit; color: inherit; }
ul, ol { margin: 0; padding: 0; }
[hidden] { display: none !important; }

/* --------------------------------------------------------------------------
   2. 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);
  text-wrap: pretty;
}
h1 { font-size: var(--text-3xl); }
h2 { font-size: var(--text-2xl); }
h3 { font-size: var(--text-xl); }
h4 { font-size: var(--text-lg); }
p { margin: 0 0 var(--space-2); }
p:last-child { margin-bottom: 0; }
strong { font-weight: var(--weight-heading); }
.display-title {
  font-size: var(--text-display);
  line-height: 1.08;
  letter-spacing: -0.015em;
  margin-bottom: var(--space-3);
}
.eyebrow {
  margin: 0 0 var(--space-2);
  font-size: var(--text-xs);
  font-weight: var(--weight-heading);
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--color-primary);
}
.section__head { margin-bottom: var(--space-6); }
.section__title {
  font-size: clamp(var(--text-2xl), 3.4vw, var(--text-4xl));
  max-width: 24ch;
  margin-bottom: var(--space-2);
}
.section__lead {
  max-width: var(--measure);
  font-size: var(--text-lg);
  color: var(--color-ink-soft);
  margin: 0;
}
.prose { max-width: var(--measure); }
.prose > * + * { margin-top: var(--space-3); }
.prose h2 { margin-top: var(--space-6); }
.prose h3 { margin-top: var(--space-4); }
.prose ul, .prose ol { padding-left: 1.3em; }
.prose li + li { margin-top: var(--space-1); }

a {
  color: inherit;
  text-decoration: underline;
  text-decoration-color: var(--color-accent);
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
  transition: text-decoration-thickness 150ms ease, color 150ms ease;
}
a:hover { text-decoration-thickness: 2px; }
mark.highlight,
.highlight {
  background-color: var(--color-highlight);
  color: var(--color-ink);
  padding: 0 4px;
  border-radius: 3px;
}

/* --------------------------------------------------------------------------
   3. 焦点与可达性
   -------------------------------------------------------------------------- */
:focus-visible {
  outline: 3px solid var(--color-focus);
  outline-offset: 3px;
  border-radius: var(--radius-sm);
}
.skip-link {
  position: fixed;
  top: var(--space-1);
  left: var(--space-1);
  z-index: 200;
  transform: translateY(-200%);
  padding: 12px 18px;
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-radius: var(--radius-md);
  font-size: var(--text-sm);
  font-weight: var(--weight-heading);
  text-decoration: none;
  box-shadow: var(--shadow-2);
  transition: transform 160ms ease;
}
.skip-link:focus { transform: translateY(0); }

/* --------------------------------------------------------------------------
   4. 布局：容器 / 章节 / 栅格
   -------------------------------------------------------------------------- */
.container {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--space-3);
}
@media (min-width: 768px) {
  .container { padding-inline: var(--gutter); }
}
.section { padding-block: var(--section-y); }
.section--lg { padding-block: var(--section-y-lg); }
.section--tight { padding-block: var(--space-6); }
.section--alt { background-color: var(--color-surface-alt); }
.section--deep { background-color: var(--color-surface-deep); }
.section--contrast {
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
}
.section--contrast h1,
.section--contrast h2,
.section--contrast h3,
.section--contrast .section__title,
.section--contrast .eyebrow { color: var(--color-contrast-ink); }
.section--contrast .section__lead,
.section--contrast p { color: color-mix(in srgb, var(--color-contrast-ink) 76%, transparent); }
.section--contrast a { color: var(--color-contrast-ink); text-decoration-color: var(--color-contrast-accent); }

.grid {
  display: grid;
  grid-template-columns: repeat(12, minmax(0, 1fr));
  gap: var(--space-3) var(--space-3);
}
@media (min-width: 960px) {
  .grid { gap: var(--gutter); }
}
.span-3, .span-4, .span-5, .span-6, .span-7, .span-8, .span-9, .span-12 { grid-column: 1 / -1; }
@media (min-width: 960px) {
  .span-3 { grid-column: span 3; }
  .span-4 { grid-column: span 4; }
  .span-5 { grid-column: span 5; }
  .span-6 { grid-column: span 6; }
  .span-7 { grid-column: span 7; }
  .span-8 { grid-column: span 8; }
  .span-9 { grid-column: span 9; }
  .span-12 { grid-column: span 12; }
  .offset-1 { grid-column-start: 2; }
  .offset-2 { grid-column-start: 3; }
  .offset-4 { grid-column-start: 5; }
}
.stack > * + * { margin-top: var(--space-3); }
.stack--tight > * + * { margin-top: var(--space-2); }
.cluster {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-2);
}

/* --------------------------------------------------------------------------
   5. 按钮
   -------------------------------------------------------------------------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-1);
  padding: 12px 20px;
  border: 0;
  border-radius: var(--radius-md);
  font-family: var(--font-heading);
  font-size: var(--text-sm);
  font-weight: var(--weight-heading);
  letter-spacing: 0.01em;
  line-height: 1.2;
  text-decoration: none;
  cursor: pointer;
  transition: background-color 160ms ease, box-shadow 160ms ease, transform 160ms ease, color 160ms ease;
}
.btn:hover { text-decoration: none; }
.btn:active { transform: translateY(0); }
.btn--primary {
  background-color: var(--color-primary);
  color: var(--color-primary-ink);
  box-shadow: var(--shadow-1);
}
.btn--primary:hover {
  background-color: color-mix(in srgb, var(--color-primary) 88%, var(--color-contrast-surface));
  box-shadow: var(--shadow-2);
  transform: translateY(-2px);
}
.btn--quiet {
  background-color: var(--color-primary-soft);
  color: var(--color-primary);
}
.btn--quiet:hover {
  background-color: color-mix(in srgb, var(--color-primary-soft) 78%, var(--color-surface-deep));
  transform: translateY(-2px);
}
.btn--accent {
  background-color: var(--color-accent);
  color: var(--color-accent-ink);
  box-shadow: var(--shadow-1);
}
.btn--accent:hover {
  box-shadow: var(--shadow-2);
  transform: translateY(-2px);
}
.btn--block { width: 100%; }

/* --------------------------------------------------------------------------
   6. 标签 / 面包屑
   -------------------------------------------------------------------------- */
.tags { display: flex; flex-wrap: wrap; gap: var(--space-1); }
.tag {
  display: inline-flex;
  align-items: center;
  padding: 5px 12px;
  border-radius: var(--radius-pill);
  background-color: var(--color-primary-soft);
  color: var(--color-primary);
  font-size: var(--text-xs);
  font-weight: var(--weight-heading);
  letter-spacing: 0.03em;
  text-decoration: none;
}
.tag--accent {
  background-color: var(--color-accent);
  color: var(--color-accent-ink);
}
.breadcrumbs {
  padding-block: var(--space-3);
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
}
.breadcrumbs ol {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 6px;
}
.breadcrumbs li + li::before {
  content: "/";
  margin-right: 6px;
  color: var(--color-line);
}
.breadcrumbs a { color: var(--color-ink-muted); text-decoration: none; }
.breadcrumbs a:hover { color: var(--color-ink); }

/* --------------------------------------------------------------------------
   7. 图片容器（展签式）
   -------------------------------------------------------------------------- */
.media, .figure__media {
  position: relative;
  overflow: hidden;
  border-radius: var(--radius-lg);
  background-color: var(--color-surface-deep);
  box-shadow: var(--shadow-1);
}
.media__img, .figure__media img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
  aspect-ratio: 16 / 9;
}
.media--wide .media__img { aspect-ratio: 21 / 9; }
.media--tall .media__img { aspect-ratio: 4 / 5; }
.media--square .media__img { aspect-ratio: 1 / 1; }
.media__caption {
  position: absolute;
  left: var(--space-2);
  bottom: var(--space-2);
  z-index: 2;
  max-width: calc(100% - var(--space-4));
  padding: 4px 10px;
  border-radius: var(--radius-sm);
  background-color: color-mix(in srgb, var(--color-contrast-surface) 70%, transparent);
  color: var(--color-contrast-ink);
  font-size: var(--text-xs);
  line-height: 1.5;
  letter-spacing: 0.02em;
}
.media--scrim::after {
  content: "";
  position: absolute;
  inset: 0;
  z-index: 1;
  background: var(--overlay-scrim);
}
.media__body {
  position: absolute;
  inset: auto var(--space-3) var(--space-3) var(--space-3);
  z-index: 2;
  color: var(--color-contrast-ink);
}
.media__body h3,
.media__body h2 { color: var(--color-contrast-ink); margin-bottom: var(--space-1); }
.media__body p { margin: 0; font-size: var(--text-sm); color: color-mix(in srgb, var(--color-contrast-ink) 82%, transparent); }
.figure { margin: 0; }
.figure__caption {
  margin-top: var(--space-1);
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
  letter-spacing: 0.02em;
}

/* --------------------------------------------------------------------------
   8. 横向吸附轨道
   -------------------------------------------------------------------------- */
.rail {
  display: flex;
  gap: var(--space-3);
  overflow-x: auto;
  scroll-snap-type: x mandatory;
  -webkit-overflow-scrolling: touch;
  padding-bottom: var(--space-3);
  scrollbar-width: thin;
  scrollbar-color: var(--color-line) transparent;
}
.rail > * {
  flex: 0 0 clamp(240px, 32%, 340px);
  scroll-snap-align: start;
}
.rail::-webkit-scrollbar { height: 6px; }
.rail::-webkit-scrollbar-thumb {
  background-color: var(--color-line);
  border-radius: var(--radius-pill);
}

/* --------------------------------------------------------------------------
   9. 数据单元
   -------------------------------------------------------------------------- */
.stat { display: grid; gap: 4px; }
.stat__value {
  font-family: var(--font-mono);
  font-size: var(--text-figure);
  font-weight: var(--weight-heading);
  line-height: 1.05;
  color: var(--color-ink);
  font-variant-numeric: tabular-nums;
}
.stat__value--sm { font-size: var(--text-2xl); color: var(--color-ink); }
.stat__label {
  font-size: var(--text-xs);
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--color-ink-muted);
}
.section--contrast .stat__value,
.section--contrast .stat__value--sm { color: var(--color-contrast-accent); }
.section--contrast .stat__label { color: color-mix(in srgb, var(--color-contrast-ink) 66%, transparent); }

/* --------------------------------------------------------------------------
   10. 折叠面板
   -------------------------------------------------------------------------- */
.fold {
  background-color: var(--color-surface-alt);
  border-radius: var(--radius-md);
  overflow: hidden;
}
.section--alt .fold,
.section--deep .fold { background-color: var(--color-surface); }
.fold + .fold { margin-top: var(--space-2); }
.fold > summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-2);
  padding: var(--space-3) var(--space-4);
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  cursor: pointer;
  list-style: none;
}
.fold > summary::-webkit-details-marker { display: none; }
.fold > summary::after {
  content: "";
  flex: none;
  width: 9px;
  height: 9px;
  margin-right: 4px;
  border-right: var(--border-thick) solid var(--color-primary);
  border-bottom: var(--border-thick) solid var(--color-primary);
  transform: rotate(45deg);
  transition: transform 180ms ease;
}
.fold[open] > summary::after { transform: rotate(-135deg); }
.fold__body {
  padding: 0 var(--space-4) var(--space-4);
  color: var(--color-ink-soft);
}
.fold__body > *:first-child { margin-top: 0; }

/* --------------------------------------------------------------------------
   11. 标签页
   -------------------------------------------------------------------------- */
.tablist {
  display: flex;
  gap: 4px;
  width: max-content;
  max-width: 100%;
  padding: 4px;
  overflow-x: auto;
  background-color: var(--color-surface-deep);
  border-radius: var(--radius-pill);
  scrollbar-width: none;
}
.tablist::-webkit-scrollbar { display: none; }
.tab {
  appearance: none;
  border: 0;
  padding: 9px 18px;
  border-radius: var(--radius-pill);
  background-color: transparent;
  color: var(--color-ink-soft);
  font-family: var(--font-heading);
  font-size: var(--text-sm);
  font-weight: var(--weight-heading);
  white-space: nowrap;
  cursor: pointer;
  transition: background-color 160ms ease, color 160ms ease, box-shadow 160ms ease;
}
.tab:hover { color: var(--color-ink); }
.tab[aria-selected="true"] {
  background-color: var(--color-surface);
  color: var(--color-accent);
  box-shadow: var(--shadow-1);
}
.tabpanel { padding-top: var(--space-4); }
.tabpanel:focus { outline: none; }

/* --------------------------------------------------------------------------
   12. 显现动效
   -------------------------------------------------------------------------- */
html.has-js [data-reveal] {
  opacity: 0;
  transform: translateY(14px);
  transition: opacity 420ms ease, transform 420ms ease;
}
html.has-js [data-reveal].is-visible {
  opacity: 1;
  transform: none;
}

/* --------------------------------------------------------------------------
   13. 共享头部
   -------------------------------------------------------------------------- */
.site-header {
  position: fixed;
  inset: 0 0 auto 0;
  z-index: 90;
  min-height: var(--header-h);
  display: flex;
  align-items: center;
  color: var(--color-ink);
  transition: background-color 220ms ease, box-shadow 220ms ease, color 220ms ease;
}
.site-header[data-scrolled="false"] {
  background-color: color-mix(in srgb, var(--color-surface) 72%, transparent);
  box-shadow: none;
}
.site-header[data-scrolled="true"],
.site-header[data-open="true"] {
  background-color: var(--color-surface);
  box-shadow: var(--shadow-1);
}
.page-hero-underlay .site-header[data-scrolled="false"] {
  background-color: transparent;
  color: var(--color-contrast-ink);
}
.page-hero-underlay .site-header[data-scrolled="false"] .brand__name,
.page-hero-underlay .site-header[data-scrolled="false"] .brand__line,
.page-hero-underlay .site-header[data-scrolled="false"] .nav__link {
  color: var(--color-contrast-ink);
}
.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-2);
  width: 100%;
  min-height: var(--header-h);
}
.scroll-progress {
  position: absolute;
  left: 0;
  bottom: 0;
  width: 100%;
  height: 2px;
  background-color: var(--color-accent);
  transform: scaleX(0);
  transform-origin: 0 50%;
  pointer-events: none;
}

/* 品牌 */
.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  color: inherit;
  flex: none;
}
.brand:hover { text-decoration: none; }
.brand__mark {
  position: relative;
  flex: none;
  width: 32px;
  height: 32px;
  border-radius: var(--radius-sm);
  background-color: var(--color-primary);
  box-shadow: var(--shadow-1);
}
.brand__mark::before {
  content: "";
  position: absolute;
  inset: 8px 7px;
  background-color: var(--color-primary-ink);
  border-radius: 2px;
  clip-path: polygon(0 62%, 100% 0, 100% 32%, 0 96%);
}
.brand__mark::after {
  content: "";
  position: absolute;
  right: 7px;
  bottom: 6px;
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background-color: var(--color-accent);
}
.brand__text { display: flex; flex-direction: column; line-height: 1.15; }
.brand__name {
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  letter-spacing: 0.02em;
  color: var(--color-ink);
}
.brand__line {
  display: none;
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: var(--color-ink-muted);
}
@media (min-width: 900px) {
  .brand__line { display: block; }
}

/* 导航 */
.site-nav { display: block; }
.nav-hint {
  margin: 0 0 var(--space-2);
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
}
.nav__list { list-style: none; display: flex; flex-direction: column; gap: 2px; }
.nav__link {
  display: block;
  padding: 13px 12px;
  border-radius: var(--radius-md);
  color: var(--color-ink-soft);
  font-size: var(--text-base);
  text-decoration: none;
  white-space: nowrap;
  transition: color 160ms ease, background-color 160ms ease;
}
.nav__link:hover {
  color: var(--color-ink);
  background-color: var(--color-primary-soft);
  text-decoration: none;
}
.nav__link[aria-current="page"] { color: var(--color-accent); font-weight: var(--weight-heading); }
.nav__link[aria-current="page"]::after {
  content: "";
  display: block;
  height: 2px;
  margin-top: 5px;
  border-radius: 2px;
  background-color: var(--color-accent);
}
.nav__foot { margin-top: var(--space-3); }

/* 头部动作区 */
.site-header__actions {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  flex: none;
}
.header-cta { display: none; }

/* 移动导航按钮 */
.nav-toggle {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: 10px 14px;
  border: 0;
  border-radius: var(--radius-pill);
  background-color: var(--color-primary-soft);
  color: var(--color-primary);
  font-family: var(--font-heading);
  font-size: var(--text-sm);
  font-weight: var(--weight-heading);
  cursor: pointer;
  transition: background-color 160ms ease, color 160ms ease;
}
.nav-toggle:hover { background-color: color-mix(in srgb, var(--color-primary-soft) 74%, var(--color-surface-deep)); }
.nav-toggle[aria-expanded="true"] {
  background-color: var(--color-primary);
  color: var(--color-primary-ink);
}
.nav-toggle__bars {
  position: relative;
  display: block;
  width: 16px;
  height: 10px;
}
.nav-toggle__bars::before,
.nav-toggle__bars::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  height: 2px;
  border-radius: 2px;
  background-color: currentColor;
  transition: transform 180ms ease, top 180ms ease, bottom 180ms ease;
}
.nav-toggle__bars::before { top: 0; }
.nav-toggle__bars::after { bottom: 0; }
.nav-toggle[aria-expanded="true"] .nav-toggle__bars::before { top: 4px; transform: rotate(45deg); }
.nav-toggle[aria-expanded="true"] .nav-toggle__bars::after { bottom: 4px; transform: rotate(-45deg); }

/* 移动端导航面板 */
@media (max-width: 899px) {
  .site-nav {
    position: fixed;
    top: var(--header-h);
    left: 0;
    right: 0;
    max-height: calc(100vh - var(--header-h));
    overflow-y: auto;
    padding: var(--space-3) var(--space-3) var(--space-4);
    background-color: var(--color-surface);
    box-shadow: var(--shadow-2);
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
    transform: translateY(-10px);
    transition: opacity 180ms ease, transform 180ms ease, visibility 0s linear 180ms;
  }
  .site-header[data-open="true"] .site-nav {
    opacity: 1;
    visibility: visible;
    pointer-events: auto;
    transform: none;
    transition-delay: 0s;
  }
}

/* 桌面端导航 */
@media (min-width: 900px) {
  .site-nav {
    display: flex;
    align-items: center;
    margin-left: auto;
  }
  .nav-hint, .nav__foot { display: none; }
  .nav__list { flex-direction: row; align-items: center; gap: var(--space-1); }
  .nav__link { padding: 9px 12px; font-size: var(--text-sm); border-radius: var(--radius-pill); }
  .nav-toggle { display: none; }
}
@media (min-width: 1080px) {
  .header-cta { display: inline-flex; }
}

/* --------------------------------------------------------------------------
   14. 共享页脚
   -------------------------------------------------------------------------- */
.site-footer {
  background-color: var(--color-surface-alt);
  color: var(--color-ink);
}
.footer-upper { padding-block: var(--space-8) var(--space-6); }
.footer-upper__inner {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-6);
}
@media (min-width: 900px) {
  .footer-upper__inner {
    grid-template-columns: minmax(240px, 1fr) 2.4fr;
    gap: var(--space-8);
  }
}
.footer-brand { max-width: 34ch; }
.brand--footer .brand__mark { width: 28px; height: 28px; }
.brand--footer .brand__name { font-size: var(--text-base); }
.brand--footer .brand__line { display: block; }
.footer-brand__note {
  margin: var(--space-2) 0 0;
  font-size: var(--text-sm);
  color: var(--color-ink-soft);
}
.footer-nav {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-4);
}
@media (min-width: 560px) {
  .footer-nav { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (min-width: 900px) {
  .footer-nav { grid-template-columns: repeat(3, minmax(0, 1fr)); }
}
.footer-col__title {
  margin: 0 0 var(--space-2);
  font-size: var(--text-xs);
  font-weight: var(--weight-heading);
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--color-ink-muted);
}
.footer-col__list {
  list-style: none;
  display: grid;
  gap: 10px;
}
.footer-col__link {
  font-size: var(--text-sm);
  color: var(--color-ink-soft);
  text-decoration: none;
}
.footer-col__link:hover {
  color: var(--color-ink);
  text-decoration: underline;
  text-decoration-color: var(--color-accent);
  text-decoration-thickness: 2px;
  text-underline-offset: 4px;
}
.footer-col__text {
  font-size: var(--text-sm);
  color: var(--color-ink-muted);
  word-break: break-word;
}
.footer-lower {
  padding-block: var(--space-4);
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-top: var(--border-thin) solid var(--color-contrast-line);
}
.footer-lower__inner { display: grid; gap: var(--space-2); }
.footer-lower__row {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--space-2) var(--space-4);
}
.footer-lower__copy {
  margin: 0;
  font-size: var(--text-xs);
  letter-spacing: 0.03em;
  color: var(--color-contrast-ink);
}
.footer-lower__links {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-3);
}
.footer-lower__links a {
  font-size: var(--text-xs);
  color: var(--color-contrast-ink);
  text-decoration: underline;
  text-decoration-color: var(--color-contrast-accent);
  text-underline-offset: 4px;
}
.footer-lower__note {
  margin: 0;
  font-size: var(--text-xs);
  line-height: 1.7;
  color: color-mix(in srgb, var(--color-contrast-ink) 68%, transparent);
}

/* --------------------------------------------------------------------------
   15. 响应式与偏好
   -------------------------------------------------------------------------- */
@media (max-width: 640px) {
  .section { padding-block: var(--space-8); }
  .section--lg { padding-block: var(--space-8); }
  .section__lead { font-size: var(--text-base); }
  .fold > summary { padding: var(--space-3); font-size: var(--text-base); }
  .fold__body { padding: 0 var(--space-3) var(--space-3); }
}

@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;
  }
  html.has-js [data-reveal] {
    opacity: 1 !important;
    transform: none !important;
  }
  .btn:hover, .btn--primary:hover, .btn--quiet:hover, .btn--accent:hover { transform: none; }
}