:root {
  --color-surface: #edeceb;
  --color-surface-alt: #e5e3e2;
  --color-surface-deep: #d9d7d6;
  --color-ink: #463f3a;
  --color-ink-soft: #6f655d;
  --color-ink-muted: #897e76;
  --color-line: #cfcdcb;
  --color-primary: #ac632a;
  --color-primary-ink: #ffffff;
  --color-primary-soft: #e4d9d0;
  --color-accent: #1f75d1;
  --color-accent-ink: #ffffff;
  --color-highlight: #c8d7e6;
  --color-focus: #1169c5;
  --color-contrast-surface: #241b14;
  --color-contrast-ink: #e7e5e4;
  --color-contrast-line: #4f4742;
  --color-contrast-accent: #3387e1;
  --overlay-scrim: linear-gradient(180deg, rgba(36, 27, 20, 0.35) 0%, rgba(36, 27, 20, 0.72) 55%, rgba(36, 27, 20, 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: 11.7px;
  --text-sm: 15.6px;
  --text-base: 18px;
  --text-lg: 24.0px;
  --text-xl: 32.0px;
  --text-2xl: 42.6px;
  --text-3xl: 56.8px;
  --text-4xl: 75.8px;
  --text-display: clamp(34px, 6.3vw, 81px);
  --text-figure: clamp(28px, 4.5vw, 58px);
  --weight-heading: 693;
  --weight-body: 400;
  --leading-body: 1.8;
  --leading-heading: 1.19;
  --tracking-heading: 0.003em;
  --radius-sm: 1px;
  --radius-md: 2px;
  --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: 1200px;
  --measure: 61ch;
  --gutter: 16px;
  --section-y: 100px;
  --section-y-lg: 140px;
}

/* ============================================================
   1. Reset 与基础排版
   ============================================================ */
*,
*::before,
*::after {
  box-sizing: border-box;
}

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

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);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

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);
}

p {
  margin: 0 0 var(--space-3);
}

p:last-child {
  margin-bottom: 0;
}

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

a:hover {
  text-decoration: underline;
  text-underline-offset: 3px;
}

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

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

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

dl,
dd,
dt,
figure,
blockquote {
  margin: 0;
}

table {
  border-collapse: collapse;
  width: 100%;
}

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

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

/* ============================================================
   2. 容器 / 栅格 / 纵向节奏
   ============================================================ */
.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--band {
  background-color: var(--color-surface-alt);
  border-block: var(--border-thin) solid var(--color-line);
}

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

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

.section-title {
  font-size: var(--text-2xl);
  max-width: 24ch;
}

.section-title--lg {
  font-size: var(--text-3xl);
}

.section-sub {
  margin-top: var(--space-2);
  max-width: var(--measure);
  font-size: var(--text-sm);
  color: var(--color-ink-soft);
}

/* ============================================================
   3. 分隔语言：实线 / 虚线 / 双线
   ============================================================ */
.rule {
  display: block;
  height: 0;
  margin: 0;
  border: 0;
  border-top: var(--border-thin) solid var(--color-line);
}

.rule--dashed {
  border-top-style: dashed;
}

.rule-double {
  display: block;
  height: 5px;
  border-top: var(--border-thin) solid var(--color-line);
  border-bottom: var(--border-thin) solid var(--color-line);
}

.contrast-block .rule,
.contrast-block .rule-double,
.site-header .rule {
  border-top-color: var(--color-contrast-line);
  border-bottom-color: var(--color-contrast-line);
}

/* ============================================================
   4. 印刷标签 / 徽标 / 标签
   ============================================================ */
.kicker,
.label-tag {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: 3px 10px;
  font-family: var(--font-body);
  font-size: var(--text-xs);
  font-weight: 600;
  letter-spacing: 0.22em;
  line-height: 1.5;
  text-transform: uppercase;
  color: var(--color-primary);
  background-color: var(--color-primary-soft);
  border: var(--border-thin) solid color-mix(in srgb, var(--color-primary) 32%, transparent);
  border-radius: var(--radius-sm);
}

.label-tag--bare {
  padding: 0;
  background-color: transparent;
  border: 0;
  border-left: var(--border-thin) solid var(--color-primary);
  padding-left: var(--space-1);
  border-radius: 0;
}

.label-tag--ink {
  color: var(--color-contrast-ink);
  background-color: transparent;
  border-color: color-mix(in srgb, var(--color-contrast-ink) 40%, transparent);
}

.badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 3px 8px;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  line-height: 1.5;
  border-radius: var(--radius-sm);
  background-color: var(--color-surface-deep);
  color: var(--color-ink-soft);
}

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

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

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

.tag {
  display: inline-flex;
  align-items: center;
  padding: 3px 10px;
  font-size: var(--text-xs);
  letter-spacing: 0.12em;
  line-height: 1.6;
  color: var(--color-ink-soft);
  background-color: var(--color-surface-alt);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-pill);
}

.tag[aria-pressed="true"],
.tag--active {
  color: var(--color-accent);
  background-color: var(--color-highlight);
  border-color: var(--color-accent);
}

/* ============================================================
   5. 按钮
   ============================================================ */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-1);
  padding: 10px 18px;
  font-family: var(--font-body);
  font-size: var(--text-sm);
  font-weight: 600;
  letter-spacing: 0.08em;
  line-height: 1.4;
  text-decoration: none;
  border: var(--border-thin) solid transparent;
  border-radius: var(--radius-sm);
  transition: background-color 0.2s ease, color 0.2s ease, border-color 0.2s ease;
}

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

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

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

.btn-ghost {
  background-color: transparent;
  border-color: color-mix(in srgb, currentColor 45%, transparent);
  color: inherit;
}

.btn-ghost:hover {
  background-color: color-mix(in srgb, currentColor 12%, transparent);
}

/* ============================================================
   6. 正文栏 / 引文 / 旁注
   ============================================================ */
.prose {
  max-width: var(--measure);
  font-size: var(--text-base);
  line-height: var(--leading-body);
  color: var(--color-ink);
}

.prose p {
  margin: 0 0 var(--space-3);
}

.prose h2 {
  margin: var(--space-6) 0 var(--space-2);
  font-size: var(--text-xl);
}

.prose h3 {
  margin: var(--space-4) 0 var(--space-2);
  font-size: var(--text-lg);
}

.prose ul,
.prose ol {
  margin: 0 0 var(--space-3);
  padding-left: 1.15em;
  list-style: disc;
}

.prose ol {
  list-style: decimal;
}

.prose li {
  margin-bottom: var(--space-1);
}

.prose a {
  color: var(--color-accent);
  text-decoration: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
}

.prose blockquote {
  margin: var(--space-4) 0;
  padding-left: var(--space-3);
  border-left: var(--border-thick) solid var(--color-primary);
  color: var(--color-ink-soft);
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  line-height: 1.5;
}

.prose code {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  background-color: var(--color-surface-alt);
  padding: 1px 5px;
  border-radius: var(--radius-sm);
}

.lede {
  font-size: var(--text-lg);
  line-height: 1.6;
  color: var(--color-ink-soft);
  max-width: var(--measure);
}

.aside-note {
  padding-top: var(--space-2);
  border-top: var(--border-thin) solid var(--color-line);
  font-size: var(--text-sm);
  line-height: 1.7;
  color: var(--color-ink-soft);
}

.aside-note .aside-label {
  display: block;
  margin-bottom: 6px;
  font-size: var(--text-xs);
  font-weight: 600;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--color-primary);
}

.aside-note--accent {
  border-top-color: var(--color-accent);
}

.aside-note--accent .aside-label {
  color: var(--color-accent);
}

/* ============================================================
   7. 面包屑
   ============================================================ */
.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-1);
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  color: var(--color-ink-muted);
}

.breadcrumb li {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
}

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

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

.breadcrumb a:hover {
  color: var(--color-primary);
}

/* ============================================================
   8. 深色数据区
   ============================================================ */
.contrast-block {
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-radius: var(--radius-md);
  padding: var(--space-6) var(--space-4);
}

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

.contrast-block a {
  color: var(--color-contrast-accent);
}

.contrast-block .kicker,
.contrast-block .label-tag {
  color: var(--color-contrast-ink);
  background-color: transparent;
  border-color: color-mix(in srgb, var(--color-contrast-ink) 38%, transparent);
}

.contrast-block .lede,
.contrast-block .aside-note {
  color: color-mix(in srgb, var(--color-contrast-ink) 74%, transparent);
}

/* ============================================================
   9. 大数字与数据牌
   ============================================================ */
.figure-xl {
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-figure);
  line-height: 1;
  letter-spacing: -0.01em;
  font-variant-numeric: tabular-nums;
  color: var(--color-ink);
}

.figure-xl--accent {
  color: var(--color-accent);
}

.figure-xl--deep {
  color: var(--color-contrast-ink);
}

.figure-md {
  font-family: var(--font-mono);
  font-weight: 600;
  font-size: var(--text-xl);
  line-height: 1.1;
  font-variant-numeric: tabular-nums;
  color: var(--color-ink);
}

.data-row {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  align-items: baseline;
  gap: var(--space-2);
  padding: var(--space-2) 0;
  border-bottom: var(--border-thin) dashed var(--color-line);
}

.data-row dt {
  font-size: var(--text-sm);
  letter-spacing: 0.08em;
  color: var(--color-ink-soft);
}

.data-row dd {
  font-family: var(--font-mono);
  font-size: var(--text-lg);
  font-variant-numeric: tabular-nums;
  color: var(--color-ink);
}

/* ============================================================
   10. 图片容器（页面阶段放占位图）
   ============================================================ */
.media-frame {
  position: relative;
  display: block;
  overflow: hidden;
  background-color: var(--color-surface-deep);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-sm);
}

.media-frame > img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

.media-frame--16x9 {
  aspect-ratio: 16 / 9;
}

.media-frame--3x2 {
  aspect-ratio: 3 / 2;
}

.media-frame--4x3 {
  aspect-ratio: 4 / 3;
}

.media-frame--1x1 {
  aspect-ratio: 1 / 1;
}

.media-frame--3x4 {
  aspect-ratio: 3 / 4;
}

.media-overlay {
  position: absolute;
  inset: auto 0 0 0;
  padding: var(--space-2);
  background-image: var(--overlay-scrim);
  color: var(--color-contrast-ink);
  font-size: var(--text-sm);
  line-height: 1.5;
}

.media-overlay .label-tag {
  color: var(--color-contrast-ink);
  background-color: transparent;
  border-color: color-mix(in srgb, var(--color-contrast-ink) 45%, transparent);
}

/* ============================================================
   11. 横向主题带
   ============================================================ */
.topic-band {
  display: flex;
  gap: var(--gutter);
  overflow-x: auto;
  scroll-snap-type: x mandatory;
  padding-bottom: var(--space-2);
  -webkit-overflow-scrolling: touch;
}

.topic-band > * {
  flex: 0 0 clamp(220px, 26vw, 300px);
  scroll-snap-align: start;
}

.topic-band::-webkit-scrollbar {
  height: 3px;
}

.topic-band::-webkit-scrollbar-track {
  background-color: var(--color-surface-deep);
}

.topic-band::-webkit-scrollbar-thumb {
  background-color: var(--color-primary);
}

/* ============================================================
   12. 可展开内容组
   ============================================================ */
.disclosure {
  border-top: var(--border-thin) dashed var(--color-line);
}

.disclosure:last-of-type {
  border-bottom: var(--border-thin) dashed var(--color-line);
}

.disclosure-trigger {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-2);
  width: 100%;
  padding: var(--space-3) 0;
  text-align: left;
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-lg);
  line-height: var(--leading-heading);
  color: var(--color-ink);
  transition: color 0.2s ease;
}

.disclosure-trigger:hover {
  color: var(--color-primary);
}

.disclosure-trigger::after {
  content: "+";
  flex: 0 0 auto;
  font-family: var(--font-mono);
  font-size: var(--text-lg);
  color: var(--color-primary);
}

.disclosure-trigger[aria-expanded="true"]::after {
  content: "–";
}

.disclosure-panel {
  padding-bottom: var(--space-3);
}

.disclosure-panel[hidden] {
  display: none;
}

/* ============================================================
   13. 站点头部
   ============================================================ */
.site-header {
  position: sticky;
  top: 0;
  z-index: 60;
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-bottom: var(--border-thin) solid var(--color-contrast-line);
  transition: background-color 0.28s ease, color 0.28s ease, border-color 0.28s ease;
}

.site-header.is-scrolled {
  background-color: var(--color-surface);
  color: var(--color-ink);
  border-bottom-color: var(--color-line);
}

.header-inner {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding: var(--space-2) var(--space-3);
  min-height: 72px;
}

.skip-link {
  position: absolute;
  left: var(--space-3);
  top: -120px;
  z-index: 120;
  padding: 10px 16px;
  background-color: var(--color-primary);
  color: var(--color-primary-ink);
  font-size: var(--text-sm);
  letter-spacing: 0.08em;
  border-radius: var(--radius-sm);
  transition: top 0.18s ease;
}

.skip-link:focus {
  top: var(--space-1);
  text-decoration: none;
}

.brand {
  display: flex;
  flex-direction: column;
  gap: 3px;
  flex: 0 0 auto;
  color: inherit;
  text-decoration: none;
  padding-right: var(--space-3);
  border-right: var(--border-thin) dashed color-mix(in srgb, currentColor 32%, transparent);
}

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

.brand-name {
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-lg);
  letter-spacing: 0.08em;
  line-height: 1.05;
}

.brand-tag {
  font-size: var(--text-xs);
  letter-spacing: 0.2em;
  line-height: 1.4;
  color: color-mix(in srgb, currentColor 70%, transparent);
}

.primary-nav {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: var(--space-4);
  flex: 1 1 auto;
  min-width: 0;
}

.nav-list {
  display: flex;
  align-items: center;
  gap: var(--space-4);
}

.nav-link {
  position: relative;
  display: inline-block;
  padding: 6px 0;
  font-size: var(--text-sm);
  font-weight: 600;
  letter-spacing: 0.1em;
  color: inherit;
  text-decoration: none;
  white-space: nowrap;
}

.nav-link:hover {
  text-decoration: none;
  color: var(--color-contrast-accent);
}

.nav-link::after {
  content: "";
  position: absolute;
  left: 0;
  right: 100%;
  bottom: 0;
  height: var(--border-thin);
  background-color: currentColor;
  transition: right 0.24s ease;
}

.nav-link:hover::after,
.nav-link[aria-current="page"]::after {
  right: 0;
}

.nav-link[aria-current="page"] {
  color: var(--color-contrast-accent);
}

.site-header.is-scrolled .nav-link:hover,
.site-header.is-scrolled .nav-link[aria-current="page"] {
  color: var(--color-primary);
}

.nav-aside {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  padding-left: var(--space-3);
  border-left: var(--border-thin) dashed color-mix(in srgb, currentColor 32%, transparent);
}

.nav-status {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.12em;
  white-space: nowrap;
  color: color-mix(in srgb, currentColor 78%, transparent);
}

.live-dot {
  width: 7px;
  height: 7px;
  flex: 0 0 auto;
  display: block;
  background-color: var(--color-contrast-accent);
  animation: yb-pulse 2.4s ease-in-out infinite;
}

.site-header.is-scrolled .live-dot {
  background-color: var(--color-accent);
}

@keyframes yb-pulse {
  0%,
  100% {
    opacity: 1;
  }
  50% {
    opacity: 0.22;
  }
}

.site-header .btn-ghost {
  border-color: color-mix(in srgb, currentColor 42%, transparent);
  color: inherit;
  padding: 8px 14px;
}

.site-header.is-scrolled .btn-ghost {
  border-color: var(--color-primary);
  color: var(--color-primary);
}

.site-header.is-scrolled .btn-ghost:hover {
  background-color: var(--color-primary);
  color: var(--color-primary-ink);
}

.nav-toggle {
  display: none;
  align-items: center;
  gap: var(--space-1);
  margin-left: auto;
  padding: 9px 12px;
  border: var(--border-thin) solid color-mix(in srgb, currentColor 42%, transparent);
  border-radius: var(--radius-sm);
  font-size: var(--text-xs);
  letter-spacing: 0.18em;
  color: inherit;
}

.nav-toggle-label {
  line-height: 1;
}

.nav-toggle-bars {
  display: inline-flex;
  flex-direction: column;
  gap: 4px;
  width: 16px;
}

.nav-toggle-bars .bar {
  display: block;
  width: 100%;
  height: var(--border-thin);
  background-color: currentColor;
  transition: transform 0.2s ease;
}

.nav-toggle[aria-expanded="true"] .bar:first-child {
  transform: translateY(2.5px) rotate(45deg);
}

.nav-toggle[aria-expanded="true"] .bar:last-child {
  transform: translateY(-2.5px) rotate(-45deg);
}

.scroll-meter {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 2px;
  overflow: hidden;
  pointer-events: none;
}

.scroll-meter > i {
  display: block;
  width: 100%;
  height: 100%;
  background-color: var(--color-primary);
  transform: scaleX(0);
  transform-origin: 0 50%;
  transition: transform 0.12s linear;
}

/* ============================================================
   14. 站点页脚
   ============================================================ */
.site-footer {
  margin-top: var(--section-y);
  padding-top: var(--space-8);
  background-color: var(--color-surface-alt);
  border-top: var(--border-thin) solid var(--color-line);
  color: var(--color-ink);
  overflow: hidden;
}

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

.footer-head {
  display: flex;
  flex-wrap: wrap;
  align-items: flex-end;
  justify-content: space-between;
  gap: var(--space-3);
}

.footer-eyebrow {
  margin: 0;
  font-size: var(--text-xs);
  font-weight: 600;
  letter-spacing: 0.24em;
  text-transform: uppercase;
  color: var(--color-primary);
}

.footer-slogan {
  margin: 0;
  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);
  color: var(--color-ink);
  text-align: right;
}

.footer-meta {
  display: grid;
  grid-template-columns: minmax(150px, 200px) minmax(0, 1fr);
  gap: var(--space-4);
  margin-top: var(--space-6);
  padding-top: var(--space-4);
  border-top: var(--border-thin) dashed var(--color-line);
}

.footer-nav {
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}

.footer-nav a {
  font-size: var(--text-sm);
  font-weight: 600;
  letter-spacing: 0.1em;
  color: var(--color-ink-soft);
}

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

.footer-facts {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(190px, 1fr));
  gap: var(--space-3);
}

.footer-facts .fact {
  padding-left: var(--space-2);
  border-left: var(--border-thin) solid var(--color-line);
}

.footer-facts dt {
  margin-bottom: 4px;
  font-size: var(--text-xs);
  letter-spacing: 0.18em;
  color: var(--color-ink-muted);
}

.footer-facts dd {
  font-size: var(--text-sm);
  line-height: 1.6;
  color: var(--color-ink);
  overflow-wrap: anywhere;
}

.footer-note {
  margin: var(--space-6) 0 0;
  padding-top: var(--space-3);
  border-top: var(--border-thin) dashed var(--color-line);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: var(--color-ink-muted);
}

.footer-wordmark {
  margin-top: var(--space-3);
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: clamp(44px, 15.5vw, 190px);
  line-height: 0.84;
  letter-spacing: 0.02em;
  white-space: nowrap;
  color: color-mix(in srgb, var(--color-ink) 17%, var(--color-surface-alt));
  user-select: none;
}

/* ============================================================
   15. 响应式
   ============================================================ */
@media (max-width: 1040px) {
  .nav-toggle {
    display: inline-flex;
  }

  .primary-nav {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    display: none;
    flex-direction: column;
    align-items: stretch;
    justify-content: flex-start;
    gap: 0;
    padding: var(--space-3);
    background-color: var(--color-surface);
    color: var(--color-ink);
    border-top: var(--border-thin) solid var(--color-line);
    border-bottom: var(--border-thin) solid var(--color-line);
    max-height: calc(100vh - 72px);
    overflow-y: auto;
  }

  .primary-nav[data-open] {
    display: flex;
  }

  .nav-list {
    flex-direction: column;
    align-items: stretch;
    gap: 0;
  }

  .nav-list li {
    border-bottom: var(--border-thin) dashed var(--color-line);
  }

  .nav-list li:last-child {
    border-bottom: 0;
  }

  .nav-link {
    display: block;
    padding: 14px 2px;
    font-size: var(--text-base);
    color: var(--color-ink);
  }

  .nav-link::after {
    display: none;
  }

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

  .nav-aside {
    flex-direction: column;
    align-items: flex-start;
    gap: var(--space-2);
    margin-top: var(--space-3);
    padding: var(--space-3) 0 0;
    border-left: 0;
    border-top: var(--border-thin) solid var(--color-line);
  }

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

  .live-dot {
    background-color: var(--color-accent);
  }

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

  .site-header .btn-ghost:hover {
    background-color: var(--color-primary);
    color: var(--color-primary-ink);
  }
}

@media (max-width: 900px) {
  .grid {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

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

  .section--lg {
    padding-block: calc(var(--section-y-lg) * 0.62);
  }

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

  .footer-nav {
    flex-direction: row;
    flex-wrap: wrap;
    gap: var(--space-3);
  }

  .footer-slogan {
    text-align: left;
    font-size: var(--text-xl);
  }

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

@media (max-width: 620px) {
  html {
    scroll-padding-top: 84px;
  }

  .header-inner {
    min-height: 64px;
    gap: var(--space-2);
  }

  .brand {
    padding-right: var(--space-2);
    border-right: 0;
  }

  .brand-name {
    font-size: var(--text-base);
  }

  .brand-tag {
    letter-spacing: 0.12em;
  }

  .primary-nav {
    max-height: calc(100vh - 64px);
  }

  .topic-band > * {
    flex-basis: 78%;
  }

  .contrast-block {
    padding: var(--space-4) var(--space-3);
  }

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

/* ============================================================
   16. 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;
  }

  .scroll-meter > i {
    transition: none;
  }
}