:root {
  --color-surface: #fdfdfd;
  --color-surface-alt: #f4f4f5;
  --color-surface-deep: #e7e8e9;
  --color-ink: #494a55;
  --color-ink-soft: #6e6f7d;
  --color-ink-muted: #797a86;
  --color-line: #dddddf;
  --color-primary: #3741c8;
  --color-primary-ink: #ffffff;
  --color-primary-soft: #e1e3f6;
  --color-accent: #c55411;
  --color-accent-ink: #ffffff;
  --color-highlight: #f3dfd3;
  --color-focus: #c14c06;
  --color-contrast-surface: #151624;
  --color-contrast-ink: #e4e4e7;
  --color-contrast-line: #43434f;
  --color-contrast-accent: #eb6414;
  --overlay-scrim: linear-gradient(180deg, rgba(21, 22, 36, 0.35) 0%, rgba(21, 22, 36, 0.72) 55%, rgba(21, 22, 36, 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: 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, 4.4vw, 56px);
  --text-figure: clamp(28px, 3.1vw, 40px);
  --weight-heading: 663;
  --weight-body: 400;
  --leading-body: 1.65;
  --leading-heading: 1.23;
  --tracking-heading: 0.009em;
  --radius-sm: 3px;
  --radius-md: 5px;
  --radius-lg: 7px;
  --radius-pill: 7px;
  --border-thin: 1px;
  --border-thick: 1px;
  --shadow-1: 0 1px 0 rgba(73, 74, 85, 0.12);
  --shadow-2: 0 2px 0 rgba(73, 74, 85, 0.18);
  --space-1: 8px;
  --space-2: 16px;
  --space-3: 24px;
  --space-4: 32px;
  --space-6: 48px;
  --space-8: 64px;
  --container: 1380px;
  --measure: 68ch;
  --gutter: 24px;
  --section-y: 67px;
  --section-y-lg: 94px;
}

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

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

body { margin: 0; }

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

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

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

p { margin: 0; }

a {
  color: var(--color-primary);
  text-decoration: none;
}

a:hover { text-decoration: underline; }

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

/* ---------------------------------------------------------
   2. 中文排版与基础文本
   --------------------------------------------------------- */
body {
  background: var(--color-surface);
  color: var(--color-ink);
  font-family: var(--font-body);
  font-size: var(--text-base);
  font-weight: var(--weight-body);
  line-height: var(--leading-body);
  letter-spacing: normal;
  overflow-wrap: break-word;
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

strong,
b { font-weight: 700; }

small { font-size: var(--text-xs); }

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

.muted { color: var(--color-ink-soft); }

.display-title {
  font-family: var(--font-heading);
  font-size: var(--text-display);
  font-weight: 800;
  line-height: 1.06;
  letter-spacing: 0.09em;
  color: var(--color-ink);
}

.figure-num {
  font-family: var(--font-mono);
  font-size: var(--text-figure);
  font-weight: 700;
  letter-spacing: -0.01em;
  line-height: 1.1;
  font-variant-numeric: tabular-nums;
}

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

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

/* ---------------------------------------------------------
   3. 跳过链接
   --------------------------------------------------------- */
.skip-link {
  position: fixed;
  top: var(--space-2);
  left: var(--space-2);
  z-index: 200;
  transform: translateY(-220%);
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  padding: 12px 18px;
  border-radius: var(--radius-md);
  font-size: var(--text-sm);
  text-decoration: none;
  transition: transform 200ms ease;
}

.skip-link:hover { text-decoration: none; }
.skip-link:focus-visible { transform: translateY(0); }

/* ---------------------------------------------------------
   4. 布局容器 / 区块 / 栅格
   --------------------------------------------------------- */
.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--tight { padding-block: var(--space-6); }

.section-head {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: var(--space-1) var(--space-4);
  margin-bottom: var(--space-4);
}

.eyebrow {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--color-accent);
  font-variant-numeric: tabular-nums;
}

.section-title {
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-2xl);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
}

.lede {
  font-size: var(--text-lg);
  line-height: 1.5;
  color: var(--color-ink-soft);
  max-width: var(--measure);
}

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

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

/* 等距刻度尺：长 96px / 短 24px，只作视觉收口 */
.rule-scale {
  height: 16px;
  border-bottom: var(--border-thin) solid var(--color-line);
  background-image:
    repeating-linear-gradient(90deg, var(--color-line) 0 1px, transparent 1px 96px),
    repeating-linear-gradient(90deg, var(--color-line) 0 1px, transparent 1px 24px);
  background-size: 100% 14px, 100% 7px;
  background-position: left bottom, left bottom;
  background-repeat: no-repeat;
}

/* ---------------------------------------------------------
   5. 头部：移动端顶栏 / 桌面端左侧固定导览轨道
   --------------------------------------------------------- */
.site-header {
  position: relative;
  z-index: 80;
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-bottom: var(--border-thin) solid var(--color-contrast-line);
}

.rail-progress {
  position: absolute;
  inset: 0 0 auto 0;
  height: 2px;
  background: color-mix(in srgb, var(--color-contrast-ink) 14%, transparent);
}

.rail-progress-bar {
  display: block;
  height: 100%;
  width: 0;
  background: var(--color-contrast-accent);
}

.header-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-2);
  min-height: 64px;
  padding: var(--space-2) var(--space-3);
}

/* 品牌说明行 */
.brand {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  color: var(--color-contrast-ink);
  text-decoration: none;
  min-width: 0;
}

.brand:hover { text-decoration: none; }

.brand-mark {
  flex: none;
  display: inline-grid;
  place-items: center;
  width: 38px;
  height: 38px;
  border-radius: var(--radius-sm);
  background: var(--color-primary);
  color: var(--color-primary-ink);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  font-weight: 700;
  letter-spacing: 0.02em;
}

.brand-words {
  display: flex;
  flex-direction: column;
  gap: 2px;
  min-width: 0;
}

.brand-name {
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: 700;
  letter-spacing: 0.07em;
  line-height: 1.15;
}

.brand-tag {
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  color: color-mix(in srgb, var(--color-contrast-ink) 62%, transparent);
  white-space: nowrap;
}

/* 抽屉开关 */
.nav-toggle {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  flex: none;
  padding: 9px 12px;
  background: transparent;
  color: var(--color-contrast-ink);
  border: var(--border-thin) solid var(--color-contrast-line);
  border-radius: var(--radius-sm);
  font-size: var(--text-sm);
  letter-spacing: 0.08em;
  cursor: pointer;
  transition: border-color 240ms ease, color 240ms ease;
}

.nav-toggle:hover {
  border-color: color-mix(in srgb, var(--color-contrast-ink) 48%, transparent);
}

.nav-toggle-bars {
  display: inline-flex;
  flex-direction: column;
  justify-content: center;
  gap: 4px;
  width: 16px;
  height: 14px;
}

.nav-toggle-bars i {
  display: block;
  height: 1px;
  background: currentColor;
  transition: transform 240ms ease, opacity 240ms ease;
}

.site-header[data-open] .nav-toggle-bars i:first-child { transform: translateY(2.5px) rotate(45deg); }
.site-header[data-open] .nav-toggle-bars i:last-child { transform: translateY(-2.5px) rotate(-45deg); }

/* 抽屉本体 */
.nav-drawer {
  display: none;
  padding-bottom: var(--space-3);
  border-top: var(--border-thin) solid var(--color-contrast-line);
}

.drawer-search {
  display: block;
  padding: var(--space-3) var(--space-3) 0;
}

.quick-search {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  padding: 12px var(--space-2);
  background: color-mix(in srgb, var(--color-contrast-ink) 8%, transparent);
  border: var(--border-thin) solid var(--color-contrast-line);
  border-radius: var(--radius-md);
  color: var(--color-contrast-ink);
  font-size: var(--text-sm);
  text-decoration: none;
  transition: border-color 240ms ease;
}

.quick-search:hover { text-decoration: none; border-color: color-mix(in srgb, var(--color-contrast-ink) 44%, transparent); }

.quick-search-key {
  flex: none;
  padding: 2px 6px;
  border: var(--border-thin) solid var(--color-contrast-line);
  border-radius: var(--radius-sm);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.12em;
  color: var(--color-contrast-accent);
}

.quick-search-text {
  flex: 1;
  min-width: 0;
  color: color-mix(in srgb, var(--color-contrast-ink) 80%, transparent);
}

/* 导航列表 */
.nav-list {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.nav-link {
  display: flex;
  align-items: baseline;
  gap: var(--space-2);
  padding: 10px var(--space-3);
  border-radius: var(--radius-sm);
  color: var(--color-contrast-ink);
  font-size: var(--text-base);
  text-decoration: none;
  transition: background-color 240ms ease, color 240ms ease;
}

.nav-link:hover {
  text-decoration: none;
  background: color-mix(in srgb, var(--color-contrast-ink) 9%, transparent);
}

.nav-idx {
  flex: none;
  min-width: 2.4ch;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  color: color-mix(in srgb, var(--color-contrast-ink) 52%, transparent);
  font-variant-numeric: tabular-nums;
}

.nav-label { letter-spacing: 0.04em; }

.nav-link[aria-current="page"] {
  background: var(--color-primary);
  color: var(--color-primary-ink);
}

.nav-link[aria-current="page"] .nav-idx {
  color: color-mix(in srgb, var(--color-primary-ink) 64%, var(--color-primary));
}

.nav-link[aria-current="page"]:hover {
  background: var(--color-primary);
}

/* 轨道底部信息 */
.rail-meta {
  display: flex;
  flex-direction: column;
  gap: 6px;
  margin-top: var(--space-4);
  padding: var(--space-3) var(--space-3) 0;
  border-top: var(--border-thin) solid var(--color-contrast-line);
}

.rail-icp {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.04em;
  color: color-mix(in srgb, var(--color-contrast-ink) 72%, transparent);
}

.rail-note {
  font-size: var(--text-xs);
  color: color-mix(in srgb, var(--color-contrast-ink) 52%, transparent);
}

/* 回到顶部 */
.to-top {
  position: fixed;
  right: var(--space-3);
  bottom: var(--space-3);
  z-index: 90;
  padding: 10px 14px;
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border: var(--border-thin) solid var(--color-contrast-line);
  border-radius: var(--radius-md);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  cursor: pointer;
  transition: border-color 240ms ease, color 240ms ease;
}

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

.to-top[hidden] { display: none; }

/* --- 移动端 / 平板：顶部抽屉 --- */
@media (max-width: 1023.98px) {
  .site-header { position: sticky; top: 0; }

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

  .nav-list {
    flex-direction: row;
    gap: var(--space-1);
    overflow-x: auto;
    padding: var(--space-3) var(--space-3) var(--space-1);
    scroll-snap-type: x proximity;
    -webkit-overflow-scrolling: touch;
  }

  .nav-item { flex: none; }

  .nav-link {
    flex: none;
    white-space: nowrap;
    padding: 9px 14px;
    font-size: var(--text-sm);
    background: color-mix(in srgb, var(--color-contrast-ink) 7%, transparent);
    scroll-snap-align: start;
  }

  .rail-meta {
    flex-direction: row;
    flex-wrap: wrap;
    gap: var(--space-1) var(--space-3);
    margin-top: var(--space-3);
    padding: var(--space-3) var(--space-3) 0;
  }
}

/* --- 桌面端：左侧固定导览轨道 --- */
@media (min-width: 1024px) {
  html {
    scroll-padding-top: var(--space-4);
    scroll-padding-left: 288px;
  }

  body { padding-left: 264px; }

  .site-header {
    position: fixed;
    top: 0;
    left: 0;
    bottom: 0;
    width: 264px;
    height: 100vh;
    display: flex;
    flex-direction: column;
    padding-bottom: var(--space-3);
    border-bottom: 0;
    border-right: var(--border-thin) solid var(--color-contrast-line);
    border-radius: 0;
  }

  .header-bar {
    display: block;
    min-height: 0;
    padding: var(--space-4) var(--space-3) var(--space-3);
  }

  .brand { width: 100%; }

  .nav-toggle { display: none; }

  .nav-drawer {
    display: flex;
    flex: 1 1 auto;
    flex-direction: column;
    min-height: 0;
    padding: var(--space-3) 0 0;
  }

  .drawer-search { display: none; }

  .site-nav { display: block; }

  .nav-list { padding-inline: var(--space-1); }

  .nav-link { padding: 10px var(--space-2); }

  .rail-meta { margin-top: auto; }
}

/* ---------------------------------------------------------
   6. 页脚：深色收口块 + 刻度
   --------------------------------------------------------- */
.site-footer {
  margin-top: var(--section-y);
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
}

.footer-scale {
  height: 16px;
  border-top: var(--border-thin) solid var(--color-contrast-line);
  background-image:
    repeating-linear-gradient(90deg, var(--color-contrast-line) 0 1px, transparent 1px 96px),
    repeating-linear-gradient(90deg, var(--color-contrast-line) 0 1px, transparent 1px 24px);
  background-size: 100% 14px, 100% 7px;
  background-position: left top, left top;
  background-repeat: no-repeat;
}

.footer-inner {
  max-width: var(--container);
  margin-inline: auto;
  padding: var(--space-8) var(--gutter) var(--space-6);
  display: grid;
  grid-template-columns: minmax(0, 1.3fr) minmax(0, 0.9fr) minmax(0, 1.4fr);
  gap: var(--space-6);
}

.footer-block { min-width: 0; }

.footer-brand {
  font-family: var(--font-heading);
  font-size: var(--text-xl);
  font-weight: var(--weight-heading);
  letter-spacing: 0.09em;
  color: var(--color-contrast-ink);
}

.footer-icp {
  margin-top: var(--space-1);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.04em;
  color: color-mix(in srgb, var(--color-contrast-ink) 68%, transparent);
}

.footer-note {
  margin-top: var(--space-2);
  max-width: 32ch;
  font-size: var(--text-sm);
  line-height: 1.6;
  color: color-mix(in srgb, var(--color-contrast-ink) 62%, transparent);
}

.footer-title {
  margin-bottom: var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: color-mix(in srgb, var(--color-contrast-ink) 56%, transparent);
}

.footer-list li + li { margin-top: 10px; }

.footer-list a {
  display: inline-block;
  font-size: var(--text-sm);
  color: var(--color-contrast-ink);
  text-decoration: none;
  border-bottom: var(--border-thin) solid transparent;
  transition: border-color 240ms ease, color 240ms ease;
}

.footer-list a:hover {
  text-decoration: none;
  color: var(--color-contrast-accent);
  border-bottom-color: var(--color-contrast-accent);
}

.footer-contact li + li { margin-top: 10px; }

.copy-btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  max-width: 100%;
  padding: 0 0 3px;
  background: transparent;
  border: 0;
  border-bottom: var(--border-thin) dashed var(--color-contrast-line);
  color: var(--color-contrast-ink);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  text-align: left;
  cursor: pointer;
  transition: color 240ms ease, border-color 240ms ease;
}

.copy-btn:hover {
  color: var(--color-contrast-accent);
  border-bottom-color: var(--color-contrast-accent);
}

.copy-btn.is-copied {
  color: var(--color-contrast-accent);
  border-bottom-color: var(--color-contrast-accent);
}

.copy-btn-tag {
  flex: none;
  font-family: var(--font-body);
  font-size: var(--text-xs);
  letter-spacing: 0.12em;
  color: color-mix(in srgb, var(--color-contrast-ink) 54%, transparent);
}

.copy-btn.is-copied .copy-btn-tag { color: var(--color-contrast-accent); }

.footer-addr {
  display: inline-block;
  font-size: var(--text-sm);
  color: color-mix(in srgb, var(--color-contrast-ink) 70%, transparent);
}

.footer-base {
  max-width: var(--container);
  margin-inline: auto;
  padding: var(--space-3) var(--gutter) var(--space-6);
  border-top: var(--border-thin) solid var(--color-contrast-line);
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--space-1) var(--space-4);
}

.footer-base-note {
  font-size: var(--text-xs);
  letter-spacing: 0.02em;
  color: color-mix(in srgb, var(--color-contrast-ink) 58%, transparent);
}

@media (max-width: 1023.98px) {
  .footer-inner {
    grid-template-columns: 1fr;
    gap: var(--space-4);
    padding-block: var(--space-6) var(--space-4);
  }

  .footer-note { max-width: none; }

  .footer-base { padding-bottom: var(--space-4); }
}

/* ---------------------------------------------------------
   7. 通用按钮
   --------------------------------------------------------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: 12px 20px;
  border: var(--border-thin) solid transparent;
  border-radius: var(--radius-md);
  font-size: var(--text-sm);
  font-weight: 500;
  letter-spacing: 0.04em;
  line-height: 1.2;
  text-decoration: none;
  cursor: pointer;
  transition: background-color 240ms ease, color 240ms ease, border-color 240ms ease;
}

.btn:hover { text-decoration: none; }

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

.btn-primary:hover {
  background: color-mix(in srgb, var(--color-primary) 84%, var(--color-contrast-surface));
}

.btn-accent {
  background: 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 {
  background: transparent;
  color: var(--color-ink);
  border-color: var(--color-line);
}

.btn-ghost:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
}

/* ---------------------------------------------------------
   8. 面包屑
   --------------------------------------------------------- */
.breadcrumb {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: var(--color-ink-muted);
}

.breadcrumb ol {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 6px;
}

.breadcrumb li { display: inline-flex; align-items: center; gap: 6px; }

.breadcrumb li + li::before {
  content: "/";
  color: var(--color-line);
}

.breadcrumb a {
  color: var(--color-ink-soft);
  text-decoration: none;
}

.breadcrumb a:hover { color: var(--color-primary); text-decoration: none; }

.breadcrumb [aria-current="page"] { color: var(--color-ink); }

/* ---------------------------------------------------------
   9. 对照表
   --------------------------------------------------------- */
.table-compare {
  width: 100%;
  border-collapse: collapse;
  font-size: var(--text-sm);
  line-height: 1.5;
}

.table-compare caption {
  caption-side: top;
  text-align: left;
  padding-bottom: var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.12em;
  color: var(--color-ink-muted);
}

.table-compare th,
.table-compare td {
  padding: 13px var(--space-2);
  text-align: left;
  vertical-align: top;
  border-bottom: var(--border-thin) solid var(--color-line);
}

.table-compare thead th {
  background: var(--color-surface-deep);
  font-weight: 600;
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  color: var(--color-ink);
}

.table-compare tbody tr { transition: background-color 200ms ease; }

.table-compare tbody tr:hover { background: var(--color-surface-alt); }

.table-compare .num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  text-align: right;
  white-space: nowrap;
}

.table-compare tbody tr.is-key { background: var(--color-highlight); }

.table-compare tbody tr.is-key:hover {
  background: color-mix(in srgb, var(--color-highlight) 82%, var(--color-surface-deep));
}

.table-compare tbody tr.is-key .num { color: var(--color-accent); font-weight: 700; }

/* ---------------------------------------------------------
   10. 内容块
   --------------------------------------------------------- */
.card {
  padding: var(--space-4);
  background: var(--color-surface);
  border-radius: var(--radius-lg);
}

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

.card--deep {
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-radius: var(--radius-lg);
}

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

/* ---------------------------------------------------------
   11. 图片容器（页面阶段放置图片使用）
   --------------------------------------------------------- */
.media-frame {
  position: relative;
  display: block;
  overflow: hidden;
  width: 100%;
  border-radius: var(--radius-md);
  background: var(--color-surface-deep);
}

.media-frame > img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  border-radius: inherit;
}

.media-frame--16x9 { aspect-ratio: 16 / 9; }
.media-frame--4x3 { aspect-ratio: 4 / 3; }
.media-frame--1x1 { aspect-ratio: 1 / 1; }
.media-frame--wide { aspect-ratio: 21 / 9; }

.media-frame__scrim {
  position: absolute;
  inset: 0;
  z-index: 1;
  background: var(--overlay-scrim);
  border-radius: inherit;
}

.media-frame__caption {
  position: absolute;
  z-index: 2;
  inset: auto var(--space-3) var(--space-3) var(--space-3);
  color: var(--color-contrast-ink);
  font-size: var(--text-sm);
  line-height: 1.4;
}

@media (max-width: 767.98px) {
  .media-frame--wide { aspect-ratio: 16 / 9; }
}

/* ---------------------------------------------------------
   12. 无障碍与响应式收尾
   --------------------------------------------------------- */
@media (max-width: 767.98px) {
  .grid { grid-template-columns: repeat(6, minmax(0, 1fr)); }
  .section { padding-block: var(--space-6); }
  .section--lg { padding-block: var(--space-8); }
  .brand-tag { display: none; }
}

@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;
  }
}