:root {
  --color-surface: #fbfbfb;
  --color-surface-alt: #f1f1f1;
  --color-surface-deep: #e3e3e3;
  --color-ink: #37322f;
  --color-ink-soft: #655d57;
  --color-ink-muted: #827973;
  --color-line: #d8d7d6;
  --color-primary: #bf580d;
  --color-primary-ink: #ffffff;
  --color-primary-soft: #f3e4da;
  --color-accent: #1273de;
  --color-accent-ink: #ffffff;
  --color-highlight: #d1e3f6;
  --color-focus: #056de0;
  --color-contrast-surface: #23170f;
  --color-contrast-ink: #e7e5e4;
  --color-contrast-line: #4e443e;
  --color-contrast-accent: #2182ed;
  --overlay-scrim: linear-gradient(180deg, rgba(35, 23, 15, 0.35) 0%, rgba(35, 23, 15, 0.72) 55%, rgba(35, 23, 15, 0.92) 100%);
  --font-heading: "Source Han Sans SC", "Noto Sans SC", SimHei, "Microsoft YaHei", sans-serif;
  --font-body: "PingFang SC", "Microsoft YaHei", "Source Han Sans SC", sans-serif;
  --font-mono: ui-monospace, Menlo, Consolas, monospace;
  --text-xs: 10.4px;
  --text-sm: 13.9px;
  --text-base: 16px;
  --text-lg: 21.3px;
  --text-xl: 28.4px;
  --text-2xl: 37.9px;
  --text-3xl: 50.5px;
  --text-4xl: 67.3px;
  --text-display: clamp(60px, 12.3vw, 158px);
  --text-figure: clamp(50px, 8.9vw, 114px);
  --weight-heading: 810;
  --weight-body: 400;
  --leading-body: 1.71;
  --leading-heading: 1.23;
  --tracking-heading: -0.021em;
  --radius-sm: 3px;
  --radius-md: 6px;
  --radius-lg: 10px;
  --radius-pill: 999px;
  --border-thin: 2px;
  --border-thick: 2px;
  --shadow-1: 4px 4px 0 #37322f;
  --shadow-2: 8px 8px 0 #37322f;
  --space-1: 8px;
  --space-2: 16px;
  --space-3: 24px;
  --space-4: 32px;
  --space-6: 48px;
  --space-8: 64px;
  --container: 1260px;
  --measure: 74ch;
  --gutter: 16px;
  --section-y: 84px;
  --section-y-lg: 118px;
}

/* ============================================================
   0. 基础重置
   ============================================================ */
*, *::before, *::after { box-sizing: border-box; }
html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}
body {
  margin: 0;
  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);
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}
img, svg, video { max-width: 100%; display: block; }
a { color: inherit; text-decoration-thickness: 2px; text-underline-offset: 3px; }
button, input, select, textarea { font: inherit; color: inherit; }
ul, ol { margin: 0; padding: 0; list-style: none; }
p { margin: 0 0 var(--space-1); }
table { border-collapse: collapse; width: 100%; }
[hidden] { display: none !important; }
:focus-visible {
  outline: 3px solid var(--color-focus);
  outline-offset: 3px;
  border-radius: var(--radius-sm);
}

/* ============================================================
   1. 排印
   ============================================================ */
h1, h2, h3, h4, h5, h6,
.h1, .h2, .h3, .h4 {
  margin: 0;
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
  text-wrap: balance;
}
h1, .h1 { font-size: var(--text-3xl); }
h2, .h2 { font-size: var(--text-2xl); }
h3, .h3 { font-size: var(--text-xl); }
h4, .h4 { font-size: var(--text-lg); }

/* 展示字号：仅首屏主标题与大数字 */
.display-title {
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-display);
  line-height: 0.9;
  letter-spacing: -0.034em;
  margin: 0;
}
.stat-figure {
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-figure);
  line-height: 0.88;
  letter-spacing: -0.03em;
  font-variant-numeric: tabular-nums;
  margin: 0;
}
.eyebrow {
  display: flex;
  align-items: center;
  gap: var(--space-1);
  margin: 0;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--color-ink-muted);
}
.eyebrow::before {
  content: "";
  flex: 0 0 auto;
  width: 30px;
  height: 5px;
  background: var(--color-primary);
}
.band--primary .eyebrow,
.band--accent .eyebrow,
.band--dark .eyebrow,
.panel--dark .eyebrow { color: color-mix(in srgb, currentColor 72%, transparent); }
.band--primary .eyebrow::before,
.panel--primary .eyebrow::before { background: var(--color-primary-ink); }
.band--accent .eyebrow::before,
.panel--accent .eyebrow::before { background: var(--color-accent-ink); }
.band--dark .eyebrow::before,
.panel--dark .eyebrow::before { background: var(--color-contrast-accent); }

.lede {
  max-width: var(--measure);
  margin: 0;
  font-size: var(--text-lg);
  line-height: 1.5;
  color: var(--color-ink-soft);
}
.band--primary .lede, .panel--primary .lede,
.band--accent .lede, .panel--accent .lede,
.band--dark .lede, .panel--dark .lede { color: inherit; }

.prose { max-width: var(--measure); font-size: var(--text-base); }
.prose > * + * { margin-top: var(--space-2); }
.prose p { margin: 0; }
.prose h2, .prose h3 { margin-top: var(--space-6); }
.prose ul, .prose ol { list-style: square; padding-left: 1.25em; }
.prose ol { list-style: decimal; }
.prose li + li { margin-top: var(--space-1); }
.prose a { color: var(--color-primary); text-decoration-color: color-mix(in srgb, var(--color-primary) 45%, transparent); }
.prose a:hover { text-decoration-color: var(--color-primary); }
.prose code {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  background: var(--color-surface-deep);
  padding: 2px 6px;
  border-radius: var(--radius-sm);
}

.mono {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.04em;
  font-variant-numeric: tabular-nums;
}
.meta-line {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-1) var(--space-3);
  margin: 0;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  color: var(--color-ink-muted);
}
.section-head {
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
  margin-bottom: var(--space-6);
}
.section-head__title { font-size: var(--text-2xl); }
.section-head--split {
  flex-direction: row;
  align-items: flex-end;
  justify-content: space-between;
  gap: var(--space-4);
}

/* ============================================================
   2. 容器、栅格与节奏
   ============================================================ */
.container {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--space-3);
}
.section { padding-block: var(--section-y); }
.section--lg { padding-block: var(--section-y-lg); }
.section--tight { padding-block: var(--space-6); }
.grid {
  display: grid;
  grid-template-columns: repeat(12, minmax(0, 1fr));
  gap: var(--gutter);
}
.col-4 { grid-column: span 4; }
.col-5 { grid-column: span 5; }
.col-6 { grid-column: span 6; }
.col-7 { grid-column: span 7; }
.col-8 { grid-column: span 8; }
.col-12 { grid-column: span 12; }
.stack { display: flex; flex-direction: column; gap: var(--space-3); }
.cluster { display: flex; flex-wrap: wrap; align-items: center; gap: var(--space-2); }

/* ============================================================
   3. 色块、面板与斜切边界
   ============================================================ */
.band { padding-block: var(--section-y); }
.band--primary { background: var(--color-primary); color: var(--color-primary-ink); }
.band--accent { background: var(--color-accent); color: var(--color-accent-ink); }
.band--dark { background: var(--color-contrast-surface); color: var(--color-contrast-ink); }
.band--alt { background: var(--color-surface-alt); }
.band--diag-top {
  clip-path: polygon(0 42px, 100% 0, 100% 100%, 0 100%);
  padding-top: calc(var(--section-y) + 42px);
}
.band--diag-bottom {
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 42px), 0 100%);
  padding-bottom: calc(var(--section-y) + 42px);
}
.band--primary .btn, .band--accent .btn, .band--dark .btn { box-shadow: 6px 6px 0 color-mix(in srgb, var(--color-contrast-surface) 55%, transparent); }

.panel {
  padding: var(--space-4);
  background: var(--color-surface-alt);
  border-radius: 0;
}
.panel--primary { background: var(--color-primary); color: var(--color-primary-ink); }
.panel--accent { background: var(--color-accent); color: var(--color-accent-ink); }
.panel--dark { background: var(--color-contrast-surface); color: var(--color-contrast-ink); }
.panel--soft { background: var(--color-primary-soft); }
.panel--diag {
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 26px), 0 100%);
  padding-bottom: calc(var(--space-4) + 26px);
}
.panel--hard { box-shadow: var(--shadow-2); }

.diag-rule {
  height: 8px;
  background: linear-gradient(96deg, var(--color-primary) 0 50%, var(--color-accent) 50% 100%);
}

/* ============================================================
   4. 按钮、标签、差异标记
   ============================================================ */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: 12px 22px;
  border: 0;
  border-radius: var(--radius-md);
  background: var(--color-surface-alt);
  color: var(--color-ink);
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: var(--text-sm);
  letter-spacing: 0.02em;
  text-decoration: none;
  cursor: pointer;
  box-shadow: var(--shadow-1);
  transition: transform 140ms ease, box-shadow 140ms ease, background-color 140ms ease, color 140ms ease;
}
.btn:hover { transform: translate(-2px, -2px); box-shadow: var(--shadow-2); }
.btn:active { transform: none; box-shadow: var(--shadow-1); }
.btn--primary { background: var(--color-primary); color: var(--color-primary-ink); }
.btn--accent { background: var(--color-accent); color: var(--color-accent-ink); }
.btn--dark { background: var(--color-contrast-surface); color: var(--color-contrast-ink); }
.btn--ghost {
  padding-inline: 0;
  background: transparent;
  color: var(--color-primary);
  box-shadow: none;
  text-decoration: underline;
  text-decoration-thickness: 3px;
}
.btn--ghost:hover { transform: translate(2px, 0); box-shadow: none; }
.btn--sm { padding: 8px 14px; font-size: var(--text-xs); }

.tag {
  display: inline-block;
  padding: 4px 10px;
  border-radius: var(--radius-pill);
  background: var(--color-surface-deep);
  color: var(--color-ink-soft);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
}
.tag--primary { background: var(--color-primary); color: var(--color-primary-ink); }
.tag--accent { background: var(--color-accent); color: var(--color-accent-ink); }
.tag--soft { background: var(--color-primary-soft); color: var(--color-primary); }

.diff {
  display: inline-block;
  padding: 0 5px;
  background: var(--color-highlight);
  color: var(--color-primary);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.02em;
}
.diff::before { content: "± "; }

/* ============================================================
   5. 头部：居中刊头 + 斜切分界带 + 可横滑栏目
   ============================================================ */
.site-header {
  position: sticky;
  top: 0;
  z-index: 80;
  background: var(--color-surface);
  transition: box-shadow 200ms ease;
}
.site-header.is-scrolled { box-shadow: 0 5px 0 color-mix(in srgb, var(--color-ink) 14%, transparent); }

.skip-link {
  position: absolute;
  left: var(--space-2);
  top: -120px;
  z-index: 120;
  padding: 12px 18px;
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  text-decoration: none;
  border-radius: var(--radius-md);
  transition: top 140ms ease;
}
.skip-link:focus { top: var(--space-2); }

.masthead { padding-block: var(--space-3) var(--space-2); }
.masthead__inner {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  gap: var(--space-2);
}
.masthead__brand { grid-column: 2; text-align: center; }
.brand {
  display: inline-flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  text-decoration: none;
  color: var(--color-ink);
}
.brand__name {
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-xl);
  line-height: 1.04;
  letter-spacing: -0.032em;
  transition: color 140ms ease;
}
.brand__sub {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
  color: var(--color-ink-muted);
}
.brand:hover .brand__name, .brand:focus-visible .brand__name { color: var(--color-primary); }

.masthead__utility {
  grid-column: 3;
  justify-self: end;
  display: flex;
  align-items: center;
  gap: var(--space-1);
  margin: 0;
  color: var(--color-ink-muted);
  white-space: nowrap;
}
.masthead__dot {
  width: 9px;
  height: 9px;
  background: var(--color-accent);
  clip-path: polygon(0 0, 100% 0, 0 100%);
}

.nav-toggle {
  grid-column: 1;
  justify-self: start;
  display: none;
  align-items: center;
  gap: var(--space-1);
  padding: 10px 14px;
  border: 0;
  border-radius: var(--radius-md);
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: var(--text-sm);
  cursor: pointer;
}
.nav-toggle__bars {
  display: inline-flex;
  flex-direction: column;
  gap: 4px;
  width: 18px;
}
.nav-toggle__bars i {
  display: block;
  height: 3px;
  background: currentColor;
  transition: transform 160ms ease, width 160ms ease;
}
.nav-toggle__bars i:nth-child(2) { width: 70%; }
.nav-toggle[aria-expanded="true"] .nav-toggle__bars i:first-child { transform: translateY(7px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] .nav-toggle__bars i:nth-child(2) { width: 0; }
.nav-toggle[aria-expanded="true"] .nav-toggle__bars i:last-child { transform: translateY(-7px) rotate(-45deg); }
.nav-toggle__label { line-height: 1; }

.header-rail {
  height: 10px;
  background: linear-gradient(96deg, var(--color-primary) 0 52%, var(--color-accent) 52% 100%);
}

.site-nav { background: var(--color-surface-alt); }
.site-nav__inner { display: flex; justify-content: center; }
.site-nav__list {
  display: flex;
  align-items: center;
  gap: var(--space-4);
  overflow-x: auto;
  scrollbar-width: none;
}
.site-nav__list::-webkit-scrollbar { display: none; }
.site-nav__list a {
  position: relative;
  display: block;
  padding: 14px 4px 16px;
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: var(--text-sm);
  letter-spacing: 0.02em;
  white-space: nowrap;
  text-decoration: none;
  color: var(--color-ink-soft);
  transition: color 140ms ease;
}
.site-nav__list a::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 9px;
  height: 4px;
  background: var(--color-accent);
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform 160ms ease;
}
.site-nav__list a:hover { color: var(--color-ink); }
.site-nav__list a:hover::after { transform: scaleX(1); }
.site-nav__list a[aria-current="page"] { color: var(--color-focus); }
.site-nav__list a[aria-current="page"]::after {
  background: var(--color-focus);
  transform: scaleX(1);
}

.scroll-progress {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 4px;
  pointer-events: none;
}
.scroll-progress__bar {
  display: block;
  width: 0;
  height: 100%;
  background: linear-gradient(90deg, var(--color-primary), var(--color-accent));
  transition: width 90ms linear;
}

/* ============================================================
   6. 页脚：反色整块 + 横向刻度
   ============================================================ */
.site-footer {
  margin-top: var(--section-y);
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
}
.site-footer__rail {
  height: 12px;
  background: linear-gradient(96deg, var(--color-primary) 0 34%, var(--color-accent) 34% 100%);
}
.site-footer__inner {
  display: grid;
  grid-template-columns: minmax(0, 1.35fr) minmax(0, 1fr);
  gap: var(--space-8);
  padding-block: var(--space-8) var(--space-6);
}
.site-footer__brand { min-width: 0; }
.site-footer__sign {
  margin: 0;
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-2xl);
  line-height: 1.04;
  letter-spacing: -0.032em;
}
.site-footer__line {
  margin: var(--space-1) 0 var(--space-3);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.1em;
  color: color-mix(in srgb, var(--color-contrast-ink) 66%, transparent);
}
.site-footer__contact {
  margin: 0;
  color: var(--color-contrast-accent);
  overflow-wrap: anywhere;
}
.site-footer__legal {
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
  min-width: 0;
}
.site-footer__links {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-4);
}
.site-footer__links a {
  position: relative;
  display: inline-block;
  padding-bottom: 8px;
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: var(--text-sm);
  letter-spacing: 0.02em;
  text-decoration: none;
  color: var(--color-contrast-ink);
}
.site-footer__links a::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 4px;
  background: var(--color-contrast-accent);
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform 160ms ease;
}
.site-footer__links a:hover::after,
.site-footer__links a:focus-visible::after { transform: scaleX(1); }
.site-footer__addr {
  margin: 0;
  color: color-mix(in srgb, var(--color-contrast-ink) 62%, transparent);
}
.site-footer__ruler {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: var(--space-2) var(--space-6);
  padding-block: var(--space-3) var(--space-6);
  color: color-mix(in srgb, var(--color-contrast-ink) 70%, transparent);
}
.site-footer__ruler .mono { letter-spacing: 0.12em; }

/* ============================================================
   7. 面包屑与目录锚点
   ============================================================ */
.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-1);
  margin: 0;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  color: var(--color-ink-muted);
}
.breadcrumb a { color: var(--color-ink-soft); text-decoration: none; }
.breadcrumb a:hover { color: var(--color-primary); }
.breadcrumb__sep { color: var(--color-line); }
.breadcrumb [aria-current="page"] { color: var(--color-ink); font-weight: 700; }

.anchor-list { display: flex; flex-direction: column; }
.anchor-list a {
  display: block;
  padding: var(--space-1) 0;
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: var(--text-sm);
  letter-spacing: 0.01em;
  text-decoration: none;
  color: var(--color-ink-soft);
  transition: color 140ms ease, transform 140ms ease;
}
.anchor-list a:hover { color: var(--color-ink); transform: translateX(2px); }
.anchor-list a[aria-current="true"],
.anchor-list a[aria-current="page"] { color: var(--color-primary); }

/* ============================================================
   8. 分段切换
   ============================================================ */
.segmented {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-1);
}
.segmented__tab {
  appearance: none;
  border: 0;
  padding: 10px 16px;
  border-radius: var(--radius-sm);
  background: var(--color-surface-alt);
  color: var(--color-ink-soft);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.04em;
  cursor: pointer;
  transition: background-color 160ms ease, color 160ms ease, box-shadow 160ms ease;
}
.segmented__tab:hover { background: var(--color-surface-deep); color: var(--color-ink); }
.segmented__tab[aria-selected="true"] {
  background: var(--color-highlight);
  color: var(--color-ink);
  font-weight: 700;
  box-shadow: inset 0 -4px 0 var(--color-accent);
}
.tabpanel { animation: tabIn 180ms ease-out both; }
@keyframes tabIn {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: none; }
}

/* ============================================================
   9. 横向册页带
   ============================================================ */
.rail { position: relative; }
.rail__track {
  display: flex;
  gap: var(--space-3);
  overflow-x: auto;
  scroll-snap-type: x mandatory;
  scroll-padding-inline: var(--space-3);
  padding: var(--space-1) 0 var(--space-3);
  scrollbar-width: thin;
  scrollbar-color: var(--color-ink-muted) transparent;
}
.rail__track::-webkit-scrollbar { height: 6px; }
.rail__track::-webkit-scrollbar-thumb { background: color-mix(in srgb, var(--color-ink-muted) 55%, transparent); border-radius: var(--radius-pill); }
.rail__track::-webkit-scrollbar-track { background: transparent; }
.rail__item {
  flex: 0 0 min(330px, 78vw);
  scroll-snap-align: start;
}
.rail__hint {
  display: block;
  margin: 0;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.12em;
  color: var(--color-ink-muted);
}

/* ============================================================
   10. 棋盘格索引与对照表
   ============================================================ */
.checker {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 0;
}
.checker__cell {
  padding: var(--space-3);
  background: var(--color-surface);
}
.checker__cell:nth-child(even) { background: var(--color-surface-deep); }

.data-table {
  width: 100%;
  font-size: var(--text-sm);
  line-height: 1.55;
}
.data-table th,
.data-table td {
  padding: 12px 14px;
  text-align: left;
  vertical-align: top;
}
.data-table thead th {
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  font-family: var(--font-heading);
  font-weight: 700;
  letter-spacing: 0.02em;
  white-space: nowrap;
}
.data-table tbody tr:nth-child(even) { background: var(--color-surface-deep); }
.data-table tbody tr + tr td { border-top: 1px solid var(--color-line); }
.data-table thead th + th,
.data-table tbody td + td { border-left: 1px solid var(--color-line); }
.data-table td.mono { font-size: var(--text-sm); }
.data-table caption {
  caption-side: bottom;
  padding-top: var(--space-1);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
  text-align: left;
}

/* ============================================================
   11. 图片容器
   ============================================================ */
.figure-frame {
  position: relative;
  display: block;
  overflow: hidden;
  border-radius: 0;
  background: var(--color-surface-deep);
}
.figure-frame__media {
  width: 100%;
  aspect-ratio: 16 / 10;
  object-fit: cover;
  border-radius: 0;
}
.figure-frame--tall .figure-frame__media { aspect-ratio: 4 / 5; }
.figure-frame--wide .figure-frame__media { aspect-ratio: 21 / 9; }
.figure-frame__placeholder {
  display: grid;
  place-items: center;
  width: 100%;
  aspect-ratio: 16 / 10;
  background-color: var(--color-surface-deep);
  background-image: repeating-linear-gradient(
    135deg,
    transparent 0 12px,
    color-mix(in srgb, var(--color-ink) 7%, transparent) 12px 24px
  );
  color: var(--color-ink-muted);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.12em;
}
.figure-frame--tall .figure-frame__placeholder { aspect-ratio: 4 / 5; }
.figure-frame--wide .figure-frame__placeholder { aspect-ratio: 21 / 9; }
.figure-frame--overlay::after {
  content: "";
  position: absolute;
  inset: 0;
  background: var(--overlay-scrim);
  pointer-events: none;
}
.figure-frame__label {
  position: absolute;
  left: var(--space-3);
  right: var(--space-3);
  bottom: var(--space-3);
  z-index: 1;
  margin: 0;
  color: var(--color-contrast-ink);
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-lg);
  letter-spacing: var(--tracking-heading);
}
.figure-frame__caption {
  margin-top: var(--space-1);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: var(--color-ink-muted);
}

/* ============================================================
   12. 显现动效
   ============================================================ */
.reveal {
  opacity: 0;
  transform: translateY(12px);
  transition: opacity 420ms ease, transform 420ms ease;
}
.reveal.is-in { opacity: 1; transform: none; }

/* ============================================================
   13. 响应式
   ============================================================ */
@media (max-width: 1100px) {
  .site-footer__inner { gap: var(--space-6); }
}
@media (max-width: 900px) {
  :root { --gutter: 12px; }
  .section { padding-block: 56px; }
  .section--lg { padding-block: 72px; }
  .col-4, .col-5, .col-6, .col-7, .col-8 { grid-column: span 12; }
  .nav-toggle { display: inline-flex; }
  .site-nav {
    background: var(--color-contrast-surface);
    color: var(--color-contrast-ink);
    max-height: 0;
    overflow: hidden;
    transition: max-height 220ms ease;
  }
  .site-nav[data-open],
  .site-nav:focus-within { max-height: calc(100vh - 140px); overflow-y: auto; }
  .site-nav__inner { justify-content: flex-start; }
  .site-nav__list {
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    overflow: visible;
    width: 100%;
  }
  .site-nav__list li + li { border-top: 1px solid var(--color-contrast-line); }
  .site-nav__list a {
    padding: 16px 2px;
    font-size: var(--text-lg);
    color: var(--color-contrast-ink);
  }
  .site-nav__list a::after { display: none; }
  .site-nav__list a[aria-current="page"] { color: var(--color-contrast-accent); }
  body[data-nav-open="true"] { overflow: hidden; }
  .site-footer { margin-top: 56px; }
  .site-footer__inner {
    grid-template-columns: minmax(0, 1fr);
    gap: var(--space-4);
    padding-block: var(--space-6) var(--space-4);
  }
  .site-footer__sign { font-size: var(--text-xl); }
}
@media (max-width: 640px) {
  .container { padding-inline: var(--space-2); }
  .masthead__inner { row-gap: var(--space-1); }
  .masthead__utility {
    grid-column: 1 / -1;
    grid-row: 2;
    justify-self: center;
  }
  .brand__name { font-size: var(--text-lg); }
  .brand__sub { font-size: var(--text-xs); letter-spacing: 0.1em; }
  .display-title { letter-spacing: -0.028em; }
  .section-head--split { flex-direction: column; align-items: flex-start; }
  .site-footer__links { gap: var(--space-3); }
  .site-footer__ruler { justify-content: flex-start; gap: var(--space-1) var(--space-3); }
  .rail__item { flex-basis: 84vw; }
}

/* ============================================================
   14. 降低动效
   ============================================================ */
@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 !important; transform: none !important; }
  .btn:hover, .anchor-list a:hover { transform: none; }
}