:root {
  --color-surface: #f6f5f5;
  --color-surface-alt: #eeecec;
  --color-surface-deep: #e2e0df;
  --color-ink: #4d443d;
  --color-ink-soft: #766a60;
  --color-ink-muted: #8b7e74;
  --color-line: #d8d5d4;
  --color-primary: #a06a40;
  --color-primary-ink: #ffffff;
  --color-primary-soft: #eae2dc;
  --color-accent: #ba5a1c;
  --color-accent-ink: #ffffff;
  --color-highlight: #ebd9ce;
  --color-focus: #b25010;
  --color-contrast-surface: #1e1814;
  --color-contrast-ink: #e7e5e4;
  --color-contrast-line: #4a4542;
  --color-contrast-accent: #dd6c22;
  --overlay-scrim: linear-gradient(180deg, rgba(30, 24, 20, 0.35) 0%, rgba(30, 24, 20, 0.72) 55%, rgba(30, 24, 20, 0.92) 100%);
  --font-heading: STZhongsong, "Source Han Serif SC", "Songti SC", SimSun, serif;
  --font-body: "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-mono: ui-monospace, Menlo, Consolas, monospace;
  --text-xs: 9.5px;
  --text-sm: 13.5px;
  --text-base: 16px;
  --text-lg: 22.6px;
  --text-xl: 32.0px;
  --text-2xl: 45.2px;
  --text-3xl: 64.0px;
  --text-4xl: 90.4px;
  --text-display: clamp(55px, 11.2vw, 144px);
  --text-figure: clamp(46px, 8.1vw, 104px);
  --weight-heading: 631;
  --weight-body: 400;
  --leading-body: 1.78;
  --leading-heading: 1.19;
  --tracking-heading: 0.029em;
  --radius-sm: 1px;
  --radius-md: 1px;
  --radius-lg: 1px;
  --radius-pill: 1px;
  --border-thin: 1px;
  --border-thick: 2px;
  --shadow-1: 0 1px 0 rgba(77, 68, 61, 0.12);
  --shadow-2: 0 2px 0 rgba(77, 68, 61, 0.18);
  --space-1: 8px;
  --space-2: 16px;
  --space-3: 24px;
  --space-4: 32px;
  --space-6: 48px;
  --space-8: 64px;
  --container: 1080px;
  --measure: 66ch;
  --gutter: 32px;
  --section-y: 78px;
  --section-y-lg: 109px;
}

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

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--space-8) * 2);
}

body, h1, h2, h3, h4, h5, p, ul, ol, li, figure, blockquote, dl, dd {
  margin: 0;
  padding: 0;
}

ul, ol { list-style: none; }

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

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

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

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

:focus-visible { outline: var(--border-thick) solid var(--color-focus); outline-offset: 3px; }

/* =========================================================
   2. 基础排版
   ========================================================= */
body {
  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);
  letter-spacing: 0.012em;
}

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

h1 { font-size: var(--text-3xl); }
h2 { font-size: var(--text-2xl); }
h3 { font-size: var(--text-xl); }
h4 { font-size: var(--text-lg); }

strong { font-weight: 600; }

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

.text-mono {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.02em;
}

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

.display-hero {
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-display);
  line-height: 1.02;
  letter-spacing: var(--tracking-heading);
}

.figure-xl {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: var(--text-figure);
  line-height: 1;
  letter-spacing: -0.02em;
  color: var(--color-accent);
}

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

/* =========================================================
   3. 布局：容器 / 分区 / 栅格
   ========================================================= */
.container {
  width: 100%;
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 var(--gutter);
}

#main-content {
  display: block;
  padding-top: calc(var(--space-8) * 2 + var(--space-2));
}

#main-content.is-flush { padding-top: 0; }

.section { padding: var(--section-y) 0; }
.section--lg { padding: var(--section-y-lg) 0; }
.section--tight { padding: var(--space-6) 0; }

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

.section--night {
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
}
.section--night h1,
.section--night h2,
.section--night h3,
.section--night h4 { color: var(--color-contrast-ink); }
.section--night :focus-visible { outline-color: var(--color-contrast-accent); }

.grid { display: grid; gap: var(--space-4); }
.grid--2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid--3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid--4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }
.grid--split { grid-template-columns: minmax(0, 2fr) minmax(0, 1fr); }
.grid--gap-sm { gap: var(--space-2); }
.grid--gap-lg { gap: var(--gutter); }

.stack > * + * { margin-top: var(--space-3); }
.stack--loose > * + * { margin-top: var(--space-6); }

/* =========================================================
   4. 分隔与框体：双线 / 票据
   ========================================================= */
.rule {
  height: 3px;
  border: 0;
  border-top: var(--border-thin) solid var(--color-line);
  border-bottom: var(--border-thin) solid var(--color-line);
  margin: var(--space-6) 0;
}
.rule--accent {
  border-top-color: var(--color-primary);
  border-bottom-color: var(--color-primary);
}
.rule--night {
  border-top-color: var(--color-contrast-line);
  border-bottom-color: var(--color-contrast-line);
}

.rule-double {
  position: relative;
  display: inline-grid;
  place-items: center;
  border: var(--border-thin) solid currentColor;
  border-radius: var(--radius-sm);
}
.rule-double::after {
  content: "";
  position: absolute;
  inset: 3px;
  border: var(--border-thin) solid currentColor;
  pointer-events: none;
}
.rule-double--current { border-color: currentColor; }
.rule-double--line { border-color: var(--color-line); }
.rule-double--line::after { border-color: var(--color-line); }

.panel {
  position: relative;
  background-color: var(--color-surface);
  border: var(--border-thick) solid var(--color-line);
  border-radius: var(--radius-sm);
  padding: var(--space-4);
}
.panel::after {
  content: "";
  position: absolute;
  inset: 5px;
  border: var(--border-thin) solid var(--color-line);
  pointer-events: none;
}
.panel--primary { border-color: var(--color-primary); }
.panel--primary::after { border-color: var(--color-primary); }
.panel--night {
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-color: var(--color-primary);
}
.panel--night::after { border-color: var(--color-contrast-line); }
.panel--night h1, .panel--night h2, .panel--night h3, .panel--night h4 { color: var(--color-contrast-ink); }

.panel__head {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--space-1) var(--space-3);
  padding-bottom: var(--space-2);
  margin-bottom: var(--space-3);
  border-bottom: var(--border-thin) solid var(--color-line);
}
.panel__title { font-size: var(--text-xl); }
.panel__meta {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
  color: var(--color-ink-muted);
}

.ticket {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: 4px 10px;
  background-color: var(--color-highlight);
  color: var(--color-accent);
  border: var(--border-thin) dashed var(--color-accent);
  border-radius: var(--radius-sm);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.2em;
  line-height: 1.4;
  white-space: nowrap;
}
.ticket--primary {
  background-color: var(--color-primary-soft);
  color: var(--color-primary);
  border-color: var(--color-primary);
}
.ticket--night {
  background-color: color-mix(in srgb, var(--color-contrast-accent) 16%, transparent);
  color: var(--color-contrast-accent);
  border-color: var(--color-contrast-accent);
}

/* =========================================================
   5. 按钮
   ========================================================= */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-1);
  padding: 10px var(--space-3);
  border: var(--border-thin) solid currentColor;
  border-radius: var(--radius-sm);
  background-color: transparent;
  color: inherit;
  font-family: var(--font-body);
  font-size: var(--text-sm);
  font-weight: var(--weight-body);
  line-height: 1.2;
  letter-spacing: 0.14em;
  cursor: pointer;
  transition: background-color 0.18s ease, color 0.18s ease, border-color 0.18s ease;
}
.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) 82%, var(--color-contrast-surface));
  border-color: color-mix(in srgb, var(--color-accent) 82%, var(--color-contrast-surface));
}
.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) 82%, var(--color-contrast-surface));
  border-color: color-mix(in srgb, var(--color-primary) 82%, var(--color-contrast-surface));
}
.btn--ghost:hover { background-color: var(--color-primary-soft); }
.btn--night {
  border-color: var(--color-contrast-accent);
  color: var(--color-contrast-accent);
}
.btn--night:hover {
  background-color: color-mix(in srgb, var(--color-contrast-accent) 18%, transparent);
}
.btn--block { width: 100%; }

/* =========================================================
   6. 头部
   ========================================================= */
.site-header {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 100;
  background-color: color-mix(in srgb, var(--color-contrast-surface) 84%, transparent);
  color: var(--color-contrast-ink);
  border-bottom: var(--border-thin) solid color-mix(in srgb, var(--color-contrast-ink) 16%, transparent);
  transition: background-color 0.24s ease, color 0.24s ease, border-color 0.24s ease;
}
.site-header[data-scrolled] {
  background-color: var(--color-surface);
  color: var(--color-ink);
  border-bottom-color: var(--color-line);
  box-shadow: var(--shadow-1);
}

.site-header__inner {
  max-width: var(--container);
  margin: 0 auto;
  padding: var(--space-3) var(--gutter) var(--space-2);
  transition: padding 0.24s ease;
}
.site-header[data-scrolled] .site-header__inner {
  padding-top: var(--space-2);
  padding-bottom: var(--space-1);
}

.skip-link {
  position: absolute;
  left: var(--space-3);
  top: -120px;
  z-index: 140;
  padding: 10px var(--space-3);
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border: var(--border-thin) solid var(--color-contrast-accent);
  font-size: var(--text-sm);
  letter-spacing: 0.14em;
  transition: top 0.18s ease;
}
.skip-link:focus { top: var(--space-2); }

.scroll-progress {
  position: absolute;
  left: 0; right: 0; bottom: 0;
  display: block;
  height: 2px;
  background-color: var(--color-contrast-accent);
  transform: scaleX(0);
  transform-origin: 0 50%;
}
.site-header[data-scrolled] .scroll-progress { background-color: var(--color-accent); }

.masthead {
  display: grid;
  grid-template-columns: minmax(0, auto) minmax(0, 1fr) auto;
  align-items: center;
  gap: var(--space-2) var(--space-4);
}

.brand {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  min-width: 0;
}
.brand__mark {
  flex: none;
  width: 42px;
  height: 42px;
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  line-height: 1;
}
.brand__text {
  display: flex;
  flex-direction: column;
  gap: 3px;
  min-width: 0;
}
.brand__name {
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-lg);
  line-height: 1.1;
  letter-spacing: var(--tracking-heading);
  white-space: nowrap;
}
.brand__line {
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
  opacity: 0.72;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.utility-nav { justify-self: end; }
.utility-nav__list { display: flex; align-items: center; }
.utility-nav__list li + li { display: flex; align-items: center; }
.utility-nav__list li + li::before {
  content: "";
  display: inline-block;
  width: var(--border-thin);
  height: 12px;
  margin: 0 var(--space-2);
  background-color: currentColor;
  opacity: 0.34;
}
.utility-nav__link {
  display: inline-block;
  padding: 4px 0;
  font-size: var(--text-sm);
  letter-spacing: 0.14em;
  border-bottom: var(--border-thin) solid transparent;
  opacity: 0.88;
  transition: opacity 0.18s ease, border-color 0.18s ease;
}
.utility-nav__link:hover {
  opacity: 1;
  border-bottom-color: currentColor;
}

.header-actions {
  justify-self: end;
  display: flex;
  align-items: center;
  gap: var(--space-2);
}

.nav-toggle {
  display: none;
  align-items: center;
  gap: var(--space-1);
  padding: 8px 12px;
  border: var(--border-thin) solid currentColor;
  border-radius: var(--radius-sm);
  color: inherit;
  font-size: var(--text-sm);
  letter-spacing: 0.14em;
  cursor: pointer;
}
.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: var(--border-thin);
  background-color: currentColor;
  transition: transform 0.2s ease, top 0.2s ease, bottom 0.2s 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: 5px; transform: rotate(-45deg); }

.primary-nav {
  margin-top: var(--space-2);
  padding: var(--space-1) 0;
  border-top: var(--border-thick) solid currentColor;
  border-bottom: var(--border-thin) solid currentColor;
}
.primary-nav__list {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0 var(--space-4);
}
.primary-nav__link {
  display: inline-block;
  padding: 6px 2px;
  font-size: var(--text-base);
  letter-spacing: 0.16em;
  border-bottom: var(--border-thick) solid transparent;
  transition: color 0.18s ease, border-color 0.18s ease;
}
.primary-nav__link:hover { border-bottom-color: currentColor; }
.primary-nav__link[aria-current="page"] {
  color: var(--color-accent);
  border-bottom-color: var(--color-accent);
}
.site-header:not([data-scrolled]) .primary-nav__link[aria-current="page"] {
  color: var(--color-contrast-accent);
  border-bottom-color: var(--color-contrast-accent);
}

/* =========================================================
   7. 页脚
   ========================================================= */
.site-footer {
  position: relative;
  margin-top: var(--section-y-lg);
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-top: var(--border-thick) solid var(--color-primary);
  overflow: hidden;
}
.site-footer::before {
  content: "";
  position: absolute;
  left: 0; right: 0; bottom: 0;
  height: 240px;
  opacity: 0.5;
  pointer-events: none;
  background-image:
    repeating-linear-gradient(90deg, color-mix(in srgb, var(--color-primary) 30%, transparent) 0 1px, transparent 1px 44px),
    repeating-linear-gradient(0deg, color-mix(in srgb, var(--color-primary) 18%, transparent) 0 1px, transparent 1px 44px),
    radial-gradient(120% 90% at 50% 130%, color-mix(in srgb, var(--color-accent) 30%, transparent), transparent 72%);
}

.site-footer__inner {
  position: relative;
  z-index: 1;
  max-width: var(--container);
  margin: 0 auto;
  padding: var(--section-y) var(--gutter) var(--space-3);
}

.footer-masthead {
  text-align: center;
  padding-bottom: var(--space-4);
  border-bottom: var(--border-thin) solid var(--color-contrast-line);
}
.footer-masthead__mark {
  width: 56px;
  height: 56px;
  margin: 0 auto var(--space-2);
  font-family: var(--font-heading);
  font-size: var(--text-xl);
  line-height: 1;
}
.footer-masthead__name {
  max-width: none;
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-xl);
  letter-spacing: var(--tracking-heading);
  color: var(--color-contrast-ink);
}
.footer-masthead__line {
  max-width: none;
  margin-top: 6px;
  font-size: var(--text-sm);
  letter-spacing: 0.18em;
  color: color-mix(in srgb, var(--color-contrast-ink) 72%, var(--color-contrast-surface));
}
.footer-masthead__meta {
  max-width: none;
  margin-top: var(--space-1);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
  color: color-mix(in srgb, var(--color-contrast-ink) 52%, var(--color-contrast-surface));
}

.footer-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  padding: var(--space-6) 0;
  border-bottom: var(--border-thin) solid var(--color-contrast-line);
}
.footer-col { padding: 0 var(--space-4); }
.footer-col:first-child { padding-left: 0; }
.footer-col:last-child { padding-right: 0; }
.footer-col + .footer-col { border-left: var(--border-thin) solid var(--color-contrast-line); }

.footer-col__title {
  display: block;
  padding-bottom: var(--space-1);
  margin-bottom: var(--space-2);
  font-size: var(--text-lg);
  letter-spacing: var(--tracking-heading);
  color: var(--color-contrast-ink);
  border-bottom: var(--border-thick) solid var(--color-primary);
}

.footer-list {
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
}
.footer-list a {
  display: inline-block;
  padding-bottom: 1px;
  font-size: var(--text-sm);
  letter-spacing: 0.08em;
  color: color-mix(in srgb, var(--color-contrast-ink) 80%, var(--color-contrast-surface));
  border-bottom: var(--border-thin) solid transparent;
  transition: color 0.18s ease, border-color 0.18s ease;
}
.footer-list a:hover {
  color: var(--color-contrast-accent);
  border-bottom-color: var(--color-contrast-accent);
}
.footer-list--plain li {
  font-size: var(--text-sm);
  line-height: 1.72;
  letter-spacing: 0.04em;
  color: color-mix(in srgb, var(--color-contrast-ink) 78%, var(--color-contrast-surface));
}
.footer-list--plain li:last-child {
  font-family: var(--font-mono);
  letter-spacing: 0.12em;
  color: color-mix(in srgb, var(--color-contrast-ink) 60%, var(--color-contrast-surface));
}

.footer-legal {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-1) var(--space-4);
  padding-top: var(--space-3);
  font-size: var(--text-xs);
  letter-spacing: 0.12em;
  color: color-mix(in srgb, var(--color-contrast-ink) 62%, var(--color-contrast-surface));
}
.footer-legal__icp { max-width: none; font-family: var(--font-mono); }
.footer-legal__contact { max-width: none; }
.footer-legal__copy { max-width: none; }
.site-footer :focus-visible { outline-color: var(--color-contrast-accent); }

/* =========================================================
   8. 通用内容组件
   ========================================================= */
.section-head {
  text-align: center;
  margin-bottom: var(--space-6);
}
.section-head__index {
  display: inline-block;
  margin-bottom: var(--space-2);
  padding: 3px 12px;
  border: var(--border-thin) dashed var(--color-accent);
  border-radius: var(--radius-sm);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.32em;
  color: var(--color-accent);
}
.section-head__title { font-size: var(--text-2xl); }
.section-head__lead {
  max-width: var(--measure);
  margin: var(--space-2) auto 0;
  font-size: var(--text-sm);
  letter-spacing: 0.06em;
  color: var(--color-ink-soft);
}
.section--night .section-head__lead {
  color: color-mix(in srgb, var(--color-contrast-ink) 70%, var(--color-contrast-surface));
}

.prose { max-width: var(--measure); }
.prose > * + * { margin-top: var(--space-3); }
.prose h2 { margin-top: var(--space-6); font-size: var(--text-xl); }
.prose h3 { margin-top: var(--space-4); font-size: var(--text-lg); }
.prose ul { list-style: none; }
.prose ul li {
  position: relative;
  padding-left: var(--space-3);
}
.prose ul li + li { margin-top: var(--space-1); }
.prose ul li::before {
  content: "—";
  position: absolute;
  left: 0;
  color: var(--color-accent);
}
.prose blockquote {
  padding: var(--space-3);
  background-color: var(--color-primary-soft);
  border-left: var(--border-thick) solid var(--color-primary);
  font-size: var(--text-sm);
  color: var(--color-ink-soft);
}

.figure-frame {
  position: relative;
  background-color: var(--color-surface);
  border: var(--border-thick) solid var(--color-line);
  border-radius: var(--radius-md);
  overflow: hidden;
}
.figure-frame__media {
  position: relative;
  aspect-ratio: 16 / 10;
  background-color: var(--color-contrast-surface);
  background-image:
    repeating-linear-gradient(90deg, color-mix(in srgb, var(--color-primary) 32%, transparent) 0 1px, transparent 1px 40px),
    repeating-linear-gradient(0deg, color-mix(in srgb, var(--color-primary) 20%, transparent) 0 1px, transparent 1px 40px),
    radial-gradient(120% 90% at 50% 118%, color-mix(in srgb, var(--color-accent) 36%, transparent), transparent 72%);
  overflow: hidden;
}
.figure-frame__media img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}
.figure-frame__caption {
  margin: 0;
  padding: var(--space-2) var(--space-3);
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
  color: var(--color-ink-soft);
  background-color: var(--color-surface);
  border-top: var(--border-thin) solid var(--color-line);
}
.figure-frame--square .figure-frame__media { aspect-ratio: 1 / 1; }
.figure-frame--wide .figure-frame__media { aspect-ratio: 21 / 9; }
.figure-frame--night {
  border-color: var(--color-contrast-line);
  background-color: var(--color-contrast-surface);
}
.figure-frame--night .figure-frame__caption {
  color: var(--color-contrast-ink);
  background-color: var(--color-contrast-surface);
  border-top-color: var(--color-contrast-line);
}

.overlay-scrim {
  position: absolute;
  inset: 0;
  z-index: 1;
  background: var(--overlay-scrim);
  pointer-events: none;
}
.overlay-text {
  position: absolute;
  left: var(--space-3);
  right: var(--space-3);
  bottom: var(--space-3);
  z-index: 2;
  color: var(--color-contrast-ink);
}

.stat {
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
}
.stat__label {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.24em;
  color: var(--color-ink-muted);
}
.stat__value {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: var(--text-figure);
  line-height: 1;
  letter-spacing: -0.02em;
  color: var(--color-accent);
}
.stat__unit {
  font-size: var(--text-sm);
  letter-spacing: 0.12em;
  color: var(--color-ink-soft);
}
.section--night .stat__value { color: var(--color-contrast-accent); }
.section--night .stat__label,
.section--night .stat__unit {
  color: color-mix(in srgb, var(--color-contrast-ink) 66%, var(--color-contrast-surface));
}

.breadcrumbs {
  padding: var(--space-3) 0;
  font-size: var(--text-xs);
  letter-spacing: 0.18em;
  color: var(--color-ink-muted);
}
.breadcrumbs__list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-1);
}
.breadcrumbs__list li { display: flex; align-items: center; }
.breadcrumbs__list li + li::before {
  content: "/";
  margin-right: var(--space-1);
  color: var(--color-line);
}
.breadcrumbs a {
  color: var(--color-ink-soft);
  border-bottom: var(--border-thin) solid transparent;
}
.breadcrumbs a:hover {
  color: var(--color-accent);
  border-bottom-color: var(--color-accent);
}
.breadcrumbs [aria-current="page"] { color: var(--color-ink); }

/* =========================================================
   9. 交互组件
   ========================================================= */
.tab-list {
  display: flex;
  flex-wrap: wrap;
  margin-bottom: var(--space-4);
  border-bottom: var(--border-thin) solid var(--color-line);
}
.tab {
  margin-bottom: -1px;
  padding: var(--space-1) var(--space-3);
  border: var(--border-thin) solid transparent;
  border-bottom: var(--border-thick) solid transparent;
  border-radius: var(--radius-sm) var(--radius-sm) 0 0;
  font-size: var(--text-sm);
  letter-spacing: 0.16em;
  color: var(--color-ink-soft);
  cursor: pointer;
  transition: color 0.18s ease, background-color 0.18s ease, border-color 0.18s ease;
}
.tab:hover { color: var(--color-ink); }
.tab[aria-selected="true"],
.tab.is-active {
  color: var(--color-accent);
  background-color: var(--color-highlight);
  border-bottom-color: var(--color-accent);
}
.tab-panel { padding-top: var(--space-2); }
.tab-panel[hidden] { display: none; }

.accordion { border-top: var(--border-thin) solid var(--color-line); }
.accordion__item { border-bottom: var(--border-thin) solid var(--color-line); }
.accordion__trigger {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
  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);
  letter-spacing: var(--tracking-heading);
  color: var(--color-ink);
  cursor: pointer;
}
.accordion__trigger::after {
  content: "+";
  flex: none;
  font-family: var(--font-mono);
  font-size: var(--text-lg);
  color: var(--color-accent);
}
.accordion__item[data-open] .accordion__trigger::after { content: "–"; }
.accordion__panel {
  padding: 0 0 var(--space-3);
  font-size: var(--text-base);
  color: var(--color-ink-soft);
}
.accordion__panel[hidden] { display: none; }

.rail {
  display: flex;
  gap: var(--space-2);
  padding-bottom: var(--space-2);
  overflow-x: auto;
  scroll-snap-type: x mandatory;
  -webkit-overflow-scrolling: touch;
}
.rail__item {
  flex: 0 0 auto;
  width: 220px;
  padding: var(--space-2);
  scroll-snap-align: start;
  background-color: var(--color-surface);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-sm);
}
.rail__item--accent { border-color: var(--color-primary); }
.rail:focus-visible { outline-offset: 4px; }

.toc {
  padding: var(--space-3);
  background-color: var(--color-surface-alt);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-sm);
}
.toc__title {
  margin-bottom: var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.28em;
  color: var(--color-ink-muted);
}
.toc__list {
  display: flex;
  flex-direction: column;
  gap: 6px;
}
.toc a {
  display: block;
  padding-left: var(--space-2);
  font-size: var(--text-sm);
  color: var(--color-ink-soft);
  border-left: var(--border-thick) solid transparent;
  transition: color 0.18s ease, border-color 0.18s ease;
}
.toc a:hover { color: var(--color-ink); }
.toc a.is-active {
  color: var(--color-accent);
  border-left-color: var(--color-accent);
}

.to-top {
  position: fixed;
  right: var(--space-3);
  bottom: var(--space-3);
  z-index: 90;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 10px 14px;
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border: var(--border-thin) solid var(--color-contrast-accent);
  border-radius: var(--radius-sm);
  font-size: var(--text-xs);
  letter-spacing: 0.2em;
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transform: translateY(8px);
  transition: opacity 0.2s ease, transform 0.2s ease, visibility 0.2s ease;
}
.to-top[data-visible] {
  opacity: 1;
  visibility: visible;
  transform: none;
}

html[data-js] [data-reveal] {
  opacity: 0;
  transform: translateY(10px);
  transition: opacity 0.42s ease, transform 0.42s ease;
}
html[data-js] [data-reveal].is-visible {
  opacity: 1;
  transform: none;
}

/* =========================================================
   10. 响应式
   ========================================================= */
@media (max-width: 1024px) {
  .grid--3, .grid--4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (max-width: 860px) {
  #main-content { padding-top: calc(var(--space-6) + var(--space-8)); }

  .masthead {
    grid-template-columns: minmax(0, 1fr) auto;
    gap: var(--space-2);
  }
  .utility-nav { display: none; }
  .brand__line { display: none; }
  .nav-toggle { display: inline-flex; }

  .primary-nav {
    margin-top: 0;
    padding: 0;
    max-height: 0;
    overflow: hidden;
    border-top-width: 0;
    border-bottom-width: 0;
    transition: max-height 0.24s ease, margin-top 0.24s ease, padding 0.24s ease;
  }
  .primary-nav[data-open] {
    max-height: 132px;
    margin-top: var(--space-2);
    padding: var(--space-2) 0;
    overflow-x: auto;
    overflow-y: hidden;
    border-top-width: var(--border-thick);
    border-bottom-width: var(--border-thin);
    scroll-snap-type: x proximity;
  }
  .primary-nav__list {
    flex-wrap: nowrap;
    justify-content: flex-start;
    gap: 0 var(--space-3);
  }
  .primary-nav__list li { flex: 0 0 auto; scroll-snap-align: start; }
  .primary-nav__link {
    font-size: var(--text-sm);
    white-space: nowrap;
    letter-spacing: 0.12em;
  }

  .grid--split, .grid--3, .grid--4 { grid-template-columns: minmax(0, 1fr); }

  .footer-grid {
    grid-template-columns: minmax(0, 1fr);
    gap: var(--space-4);
    padding: var(--space-4) 0;
  }
  .footer-col { padding: 0; }
  .footer-col + .footer-col {
    padding-top: var(--space-4);
    border-left: 0;
    border-top: var(--border-thin) solid var(--color-contrast-line);
  }
  .site-footer__inner { padding-left: var(--space-3); padding-right: var(--space-3); }
  .footer-masthead__name { font-size: var(--text-lg); }
  .footer-legal { flex-direction: column; align-items: flex-start; }

  .rail__item { width: 186px; }
  .section-head__title { font-size: var(--text-xl); }
}

@media (max-width: 680px) {
  .grid--2 { grid-template-columns: minmax(0, 1fr); }
  .container { padding: 0 var(--space-3); }
}

@media (max-width: 560px) {
  .site-header__inner {
    padding-left: var(--space-2);
    padding-right: var(--space-2);
  }
  .brand__mark { width: 34px; height: 34px; font-size: var(--text-base); }
  .brand__name { font-size: var(--text-base); }
  .header-actions { gap: var(--space-1); }
  .header-actions .btn { padding: 8px 10px; letter-spacing: 0.08em; }
  .nav-toggle__text { display: none; }
}

/* =========================================================
   11. 动效降级
   ========================================================= */
@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;
  }
  html[data-js] [data-reveal] {
    opacity: 1 !important;
    transform: none !important;
  }
  .to-top { transition: none; }
}