:root {
  --color-surface: #f2f2f2;
  --color-surface-alt: #e9e9ea;
  --color-surface-deep: #ddddde;
  --color-ink: #40444a;
  --color-ink-soft: #656972;
  --color-ink-muted: #797e86;
  --color-line: #d2d3d4;
  --color-primary: #3f6fc0;
  --color-primary-ink: #ffffff;
  --color-primary-soft: #d9e0eb;
  --color-accent: #5c7d07;
  --color-accent-ink: #ffffff;
  --color-highlight: #d7ddc8;
  --color-focus: #547501;
  --color-contrast-surface: #0f1217;
  --color-contrast-ink: #e4e5e7;
  --color-contrast-line: #3e4045;
  --color-contrast-accent: #b2f10e;
  --overlay-scrim: linear-gradient(180deg, rgba(15, 18, 23, 0.35) 0%, rgba(15, 18, 23, 0.72) 55%, rgba(15, 18, 23, 0.92) 100%);
  --font-heading: "Source Han Serif SC", "Songti SC", Georgia, serif;
  --font-body: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --font-mono: ui-monospace, Menlo, Consolas, monospace;
  --text-xs: 8.9px;
  --text-sm: 12.6px;
  --text-base: 15px;
  --text-lg: 21.2px;
  --text-xl: 30.0px;
  --text-2xl: 42.4px;
  --text-3xl: 60.0px;
  --text-4xl: 84.8px;
  --text-display: clamp(37px, 7.6vw, 97px);
  --text-figure: clamp(31px, 5.5vw, 70px);
  --weight-heading: 736;
  --weight-body: 400;
  --leading-body: 1.67;
  --leading-heading: 1.23;
  --tracking-heading: -0.005em;
  --radius-sm: 1px;
  --radius-md: 2px;
  --radius-lg: 4px;
  --radius-pill: 4px;
  --border-thin: 1px;
  --border-thick: 2px;
  --shadow-1: 0 1px 0 rgba(64, 68, 74, 0.12);
  --shadow-2: 0 2px 0 rgba(64, 68, 74, 0.18);
  --space-1: 7px;
  --space-2: 14px;
  --space-3: 21px;
  --space-4: 28px;
  --space-6: 42px;
  --space-8: 56px;
  --container: 1180px;
  --measure: 74ch;
  --gutter: 21px;
  --section-y: 73px;
  --section-y-lg: 102px;
}

/* ============================================================
   1. RESET
   ============================================================ */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body { margin: 0; }
h1, h2, h3, h4, h5, h6, p, figure, blockquote, dl, dd, pre { margin: 0; }
ul, ol { margin: 0; padding: 0; list-style: none; }
img, svg, video { display: block; max-width: 100%; }
button, input, select, textarea { font: inherit; color: inherit; }
button { background: none; border: 0; padding: 0; cursor: pointer; }
a { color: inherit; text-decoration: none; }
table { border-collapse: collapse; width: 100%; }
strong, b { font-weight: var(--weight-heading); }

/* ============================================================
   2. 基础排版 · 中文正文
   ============================================================ */
html { scroll-padding-top: 108px; }
@media (prefers-reduced-motion: no-preference) { html { scroll-behavior: smooth; } }

body {
  font-family: var(--font-body);
  font-size: var(--text-base);
  line-height: var(--leading-body);
  font-weight: var(--weight-body);
  color: var(--color-ink);
  background-color: var(--color-surface);
  min-height: 100vh;
  overflow-x: hidden;
}

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
  text-wrap: balance;
}

.mono { font-family: var(--font-mono); font-size: var(--text-xs); letter-spacing: 0.06em; }
.serif { font-family: var(--font-heading); font-weight: var(--weight-heading); }

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

:focus-visible {
  outline: var(--border-thick) solid var(--color-focus);
  outline-offset: 2px;
}
.panel-dark :focus-visible,
.site-footer :focus-visible,
.site-header :focus-visible {
  outline-color: var(--color-contrast-accent);
}

/* ============================================================
   3. 布局骨架
   ============================================================ */
.wrap {
  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--alt { background-color: var(--color-surface-alt); }

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

.rail-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--space-6);
}
@media (min-width: 900px) {
  .rail-layout {
    grid-template-columns: minmax(0, 3fr) minmax(0, 9fr);
    gap: var(--gutter);
    align-items: start;
  }
}

.grid { display: grid; gap: var(--gutter); grid-template-columns: minmax(0, 1fr); }
@media (min-width: 720px) {
  .grid--2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .grid--3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
}

/* ============================================================
   4. 跳转链接
   ============================================================ */
.skip-link {
  position: absolute;
  left: var(--space-2);
  top: -200px;
  z-index: 300;
  display: inline-block;
  padding: var(--space-2) var(--space-3);
  background-color: var(--color-primary);
  color: var(--color-primary-ink);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.06em;
  border-radius: var(--radius-sm);
  transition: top 0.16s linear;
}
.skip-link:focus { top: var(--space-2); }

/* ============================================================
   5. 头部
   ============================================================ */
.site-header {
  position: sticky;
  top: 0;
  z-index: 120;
  --hdr-ink: var(--color-contrast-ink);
  --hdr-soft: color-mix(in srgb, var(--color-contrast-ink) 58%, var(--color-contrast-surface));
  --hdr-line: var(--color-contrast-line);
  --hdr-accent: var(--color-contrast-accent);
  --hdr-bg: var(--color-contrast-surface);
  position: sticky;
  background-color: var(--hdr-bg);
  color: var(--hdr-ink);
  border-bottom: var(--border-thin) solid var(--hdr-line);
  transition: background-color 0.18s linear, color 0.18s linear, border-color 0.18s linear;
}
.site-header.is-scrolled {
  --hdr-ink: var(--color-ink);
  --hdr-soft: var(--color-ink-muted);
  --hdr-line: var(--color-line);
  --hdr-accent: var(--color-accent);
  --hdr-bg: var(--color-surface);
}

.site-header__progress {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: var(--border-thick);
  display: block;
  pointer-events: none;
}
.site-header__progress-bar {
  display: block;
  height: 100%;
  width: 100%;
  transform: scaleX(0);
  transform-origin: 0 50%;
  background-color: var(--hdr-accent);
}

.site-header__meta {
  border-bottom: var(--border-thin) solid var(--hdr-line);
}
.site-header__meta-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
  padding-block: var(--space-1);
  color: var(--hdr-soft);
}
.site-header__meta-code { color: var(--hdr-accent); }
.site-header__meta-mid { display: none; }
@media (min-width: 720px) { .site-header__meta-mid { display: inline; } }
.site-header__meta-end { display: none; }
@media (min-width: 1000px) { .site-header__meta-end { display: inline; } }

.site-header__inner {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
  padding-block: var(--space-2);
}

/* 品牌 */
.brand {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  min-width: 0;
}
.brand__mark {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 38px;
  height: 38px;
  flex: 0 0 auto;
  background-color: var(--color-primary);
  color: var(--color-primary-ink);
  font-size: var(--text-sm);
  letter-spacing: 0.02em;
  border-radius: var(--radius-sm);
}
.brand__text { display: flex; flex-direction: column; min-width: 0; }
.brand__name {
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-lg);
  line-height: 1.05;
  color: var(--hdr-ink);
}
.brand__tagline {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: var(--hdr-soft);
  margin-top: 3px;
}

/* 移动导航按钮 */
.nav-toggle {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-1) var(--space-2);
  border: var(--border-thin) solid var(--hdr-line);
  border-radius: var(--radius-sm);
  color: var(--hdr-ink);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
}
.nav-toggle__bars {
  position: relative;
  display: block;
  width: 15px;
  height: 9px;
}
.nav-toggle__bars::before,
.nav-toggle__bars::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  height: var(--border-thin);
  background-color: var(--hdr-ink);
  transition: transform 0.16s linear, top 0.16s linear, bottom 0.16s linear;
}
.nav-toggle__bars::before { top: 0; }
.nav-toggle__bars::after { bottom: 0; }
.nav-toggle[aria-expanded="true"] .nav-toggle__bars::before { top: 4px; transform: rotate(45deg); }
.nav-toggle[aria-expanded="true"] .nav-toggle__bars::after { bottom: 4px; transform: rotate(-45deg); }

/* 导航 */
.site-nav {
  display: none;
  position: absolute;
  top: 100%;
  left: calc(var(--gutter) * -1);
  right: calc(var(--gutter) * -1);
  max-height: min(72vh, 520px);
  overflow-y: auto;
  padding: var(--space-2) var(--gutter) var(--space-3);
  background-color: var(--color-contrast-surface);
  border-top: var(--border-thin) solid var(--color-contrast-line);
  border-bottom: var(--border-thin) solid var(--color-contrast-line);
}
.site-nav[data-open] { display: block; }
.site-nav__list { display: block; }
.site-nav__item { border-top: var(--border-thin) solid var(--color-contrast-line); }
.site-nav__item:first-child { border-top: 0; }
.site-nav__link {
  display: flex;
  align-items: baseline;
  gap: var(--space-2);
  padding: var(--space-2) 0 var(--space-2) var(--space-2);
  border-left: var(--border-thick) solid transparent;
  color: var(--color-contrast-ink);
  font-size: var(--text-base);
  transition: border-color 0.14s linear, color 0.14s linear;
}
.site-nav__no {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: color-mix(in srgb, var(--color-contrast-ink) 58%, var(--color-contrast-surface));
}
.site-nav__link:hover,
.site-nav__link:focus-visible {
  border-left-color: var(--color-contrast-accent);
  color: var(--color-contrast-accent);
}
.site-nav__link[aria-current="page"] {
  border-left-color: var(--color-contrast-accent);
  color: var(--color-contrast-accent);
}
.site-nav__link[aria-current="page"] .site-nav__no { color: var(--color-contrast-accent); }

@media (min-width: 900px) {
  .nav-toggle { display: none; }
  .site-nav {
    position: static;
    display: block;
    max-height: none;
    overflow: visible;
    padding: 0;
    background-color: transparent;
    border: 0;
  }
  .site-nav__list { display: flex; flex-wrap: wrap; align-items: center; gap: 2px; }
  .site-nav__item { border-top: 0; }
  .site-nav__link {
    padding: var(--space-2) var(--space-2);
    border-left: var(--border-thick) solid transparent;
    color: var(--hdr-ink);
    font-size: var(--text-sm);
  }
  .site-nav__no { color: var(--hdr-soft); }
  .site-nav__link:hover,
  .site-nav__link:focus-visible,
  .site-nav__link[aria-current="page"] {
    border-left-color: var(--hdr-accent);
    color: var(--hdr-accent);
    background-color: color-mix(in srgb, var(--hdr-ink) 6%, transparent);
  }
  .site-nav__link[aria-current="page"] .site-nav__no { color: var(--hdr-accent); }
}

/* ============================================================
   6. 页脚
   ============================================================ */
.site-footer {
  position: relative;
  margin-top: var(--section-y-lg);
  padding-top: var(--section-y);
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-top: var(--border-thick) solid var(--color-contrast-accent);
}

.site-footer__top {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--space-6);
  padding-bottom: var(--space-6);
  border-bottom: var(--border-thin) solid var(--color-contrast-line);
}
@media (min-width: 1000px) {
  .site-footer__top {
    grid-template-columns: minmax(0, 3fr) minmax(0, 9fr);
    gap: var(--gutter);
  }
}

.site-footer__brand { max-width: 34ch; }
.site-footer__code {
  display: block;
  color: var(--color-contrast-accent);
  margin-bottom: var(--space-2);
}
.site-footer__claim {
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-lg);
  line-height: var(--leading-heading);
  color: var(--color-contrast-ink);
}

.site-footer__nav {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--space-4);
}
@media (min-width: 640px) {
  .site-footer__nav { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (min-width: 1000px) {
  .site-footer__nav { grid-template-columns: repeat(4, minmax(0, 1fr)); gap: var(--gutter); }
}

.site-footer__heading {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-weight: var(--weight-body);
  letter-spacing: 0.08em;
  color: var(--color-contrast-accent);
  padding-bottom: var(--space-1);
  border-bottom: var(--border-thin) solid var(--color-contrast-line);
  margin-bottom: var(--space-2);
}
.site-footer__list li {
  padding-block: var(--space-1);
  border-bottom: var(--border-thin) solid color-mix(in srgb, var(--color-contrast-line) 55%, transparent);
  color: color-mix(in srgb, var(--color-contrast-ink) 74%, var(--color-contrast-surface));
  font-size: var(--text-sm);
}
.site-footer__list a {
  display: inline-block;
  color: color-mix(in srgb, var(--color-contrast-ink) 82%, var(--color-contrast-surface));
  border-left: var(--border-thick) solid transparent;
  padding-left: var(--space-2);
  transition: color 0.14s linear, border-color 0.14s linear;
}
.site-footer__list a:hover,
.site-footer__list a:focus-visible {
  color: var(--color-contrast-accent);
  border-left-color: var(--color-contrast-accent);
}
.site-footer__contact li { border-bottom-style: dashed; }
.site-footer__note {
  color: color-mix(in srgb, var(--color-contrast-ink) 58%, var(--color-contrast-surface));
  line-height: 1.6;
  margin-top: var(--space-2);
}

.site-footer__markwrap {
  padding-top: var(--space-6);
  overflow: hidden;
}
.site-footer__mark {
  display: block;
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-display);
  line-height: 0.86;
  letter-spacing: -0.02em;
  white-space: nowrap;
  color: color-mix(in srgb, var(--color-contrast-ink) 20%, var(--color-contrast-surface));
}

.site-footer__base {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2) var(--space-4);
  align-items: baseline;
  justify-content: space-between;
  padding-block: var(--space-3);
  border-top: var(--border-thin) solid var(--color-contrast-line);
  margin-top: var(--space-4);
}
.site-footer__base .site-footer__note { margin-top: 0; }

/* ============================================================
   7. 返回顶部
   ============================================================ */
.to-top {
  position: fixed;
  right: var(--space-3);
  bottom: var(--space-3);
  z-index: 110;
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: var(--space-2);
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  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: 0.06em;
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.18s linear, visibility 0.18s linear;
}
.to-top.is-visible { opacity: 1; visibility: visible; }
.to-top__no { color: var(--color-contrast-accent); }
.to-top:hover, .to-top:focus-visible { border-color: var(--color-contrast-accent); }

/* ============================================================
   8. 通用组件
   ============================================================ */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-2) var(--space-3);
  border: var(--border-thin) solid var(--color-ink);
  border-radius: var(--radius-sm);
  background-color: transparent;
  color: var(--color-ink);
  font-size: var(--text-sm);
  line-height: 1.2;
  transition: background-color 0.14s linear, color 0.14s linear, border-color 0.14s linear;
}
.btn__no { font-family: var(--font-mono); font-size: var(--text-xs); letter-spacing: 0.06em; }
.btn--primary {
  background-color: var(--color-primary);
  border-color: var(--color-primary);
  color: var(--color-primary-ink);
}
.btn--accent {
  background-color: var(--color-accent);
  border-color: var(--color-accent);
  color: var(--color-accent-ink);
}
.btn--ghost {
  border-color: var(--color-line);
  background-color: var(--color-surface-alt);
  color: var(--color-ink);
}
.btn:hover, .btn:focus-visible { border-color: var(--color-focus); }
.btn--primary:hover, .btn--primary:focus-visible { background-color: var(--color-focus); border-color: var(--color-focus); color: var(--color-primary-ink); }
.btn--accent:hover, .btn--accent:focus-visible { background-color: var(--color-focus); border-color: var(--color-focus); color: var(--color-accent-ink); }
.panel-dark .btn { border-color: var(--color-contrast-line); color: var(--color-contrast-ink); }
.panel-dark .btn--primary { background-color: var(--color-contrast-accent); border-color: var(--color-contrast-accent); color: var(--color-contrast-surface); }

.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: var(--color-ink-muted);
}
.breadcrumb a {
  color: var(--color-ink-soft);
  border-bottom: var(--border-thin) solid var(--color-line);
}
.breadcrumb a:hover, .breadcrumb a:focus-visible { color: var(--color-primary); border-bottom-color: var(--color-primary); }
.breadcrumb__sep::before { content: "/"; }

.section-head {
  display: grid;
  gap: var(--space-2);
  padding-left: var(--space-3);
  border-left: var(--border-thick) solid var(--color-primary);
  margin-bottom: var(--space-6);
}
.section-head__kicker {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  color: var(--color-ink-muted);
  text-transform: uppercase;
}
.section-head__title {
  font-size: var(--text-2xl);
  color: var(--color-ink);
}
.section-head__desc {
  max-width: var(--measure);
  color: var(--color-ink-soft);
}
.panel-dark .section-head { border-left-color: var(--color-contrast-accent); }
.panel-dark .section-head__title { color: var(--color-contrast-ink); }
.panel-dark .section-head__kicker { color: var(--color-contrast-accent); }
.panel-dark .section-head__desc { color: color-mix(in srgb, var(--color-contrast-ink) 72%, var(--color-contrast-surface)); }

.tag {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: 3px var(--space-2);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-sm);
  background-color: var(--color-surface-alt);
  color: var(--color-ink-soft);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  white-space: nowrap;
}
.tag--primary { background-color: var(--color-primary); border-color: var(--color-primary); color: var(--color-primary-ink); }
.tag--accent { background-color: var(--color-accent); border-color: var(--color-accent); color: var(--color-accent-ink); }
.tag--dark {
  background-color: var(--color-contrast-surface);
  border-color: var(--color-contrast-line);
  color: var(--color-contrast-accent);
}

/* 图片容器 */
.figure {
  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);
}
.figure__img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}
.figure--wide { aspect-ratio: 16 / 7; }
.figure--tall { aspect-ratio: 3 / 5; }
.figure--square { aspect-ratio: 1 / 1; }
.figure--band { aspect-ratio: 21 / 6; }
.figure__caption {
  display: block;
  padding-top: var(--space-1);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: var(--color-ink-muted);
}
.figure__scrim {
  position: absolute;
  inset: 0;
  background: var(--overlay-scrim);
  pointer-events: none;
}
.figure__label {
  position: absolute;
  left: var(--space-3);
  right: var(--space-3);
  bottom: var(--space-3);
  color: var(--color-contrast-ink);
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-lg);
  line-height: var(--leading-heading);
}
.figure__label .mono { color: var(--color-contrast-accent); display: block; margin-bottom: var(--space-1); }

/* 图文咬合 */
.overlap { position: relative; display: block; }
.overlap__media { display: block; }
.overlap__text {
  position: relative;
  z-index: 2;
  max-width: 46ch;
  margin-top: calc(var(--space-8) * -1);
  margin-left: 0;
  padding: var(--space-4);
  background-color: var(--color-surface);
  border: var(--border-thin) solid var(--color-line);
  border-left: var(--border-thick) solid var(--color-primary);
  border-radius: var(--radius-sm);
}
.overlap__text h3 { font-size: var(--text-xl); margin-bottom: var(--space-2); }
.overlap__text p { color: var(--color-ink-soft); }
@media (min-width: 720px) {
  .overlap__text { margin-left: var(--space-6); }
}
@media (max-width: 719px) {
  .overlap__text { margin-top: calc(var(--space-4) * -1); }
}

/* 数字墙 */
.number-wall {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: var(--gutter);
  align-items: end;
}
.number-wall__item {
  padding-top: var(--space-2);
  border-top: var(--border-thick) solid var(--color-line);
}
.number-wall__item:nth-child(2n) { margin-top: var(--space-4); }
.number-wall__value {
  display: block;
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-figure);
  line-height: 0.95;
  letter-spacing: var(--tracking-heading);
  color: var(--color-primary);
}
.number-wall__item:nth-child(2n) .number-wall__value { color: var(--color-accent); }
.number-wall__unit {
  display: block;
  margin-top: var(--space-1);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: var(--color-ink-muted);
}
.panel-dark .number-wall__item { border-top-color: var(--color-contrast-line); }
.panel-dark .number-wall__value { color: var(--color-contrast-accent); }
.panel-dark .number-wall__unit { color: color-mix(in srgb, var(--color-contrast-ink) 62%, var(--color-contrast-surface)); }

/* 时间轴轨道 */
.timeline-rail { position: relative; padding-left: var(--space-6); }
.timeline-rail::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: var(--border-thin);
  background-color: var(--color-line);
}
.timeline-rail__item {
  position: relative;
  padding-block: var(--space-3);
  border-bottom: var(--border-thin) solid var(--color-line);
}
.timeline-rail__item::before {
  content: "";
  position: absolute;
  left: calc(var(--space-6) * -1 - var(--space-1));
  top: calc(var(--space-3) + var(--space-1));
  width: var(--space-2);
  height: var(--space-2);
  background-color: var(--color-primary);
  border-radius: var(--radius-sm);
}
.timeline-rail__item[data-state="current"]::before { background-color: var(--color-contrast-accent); outline: var(--border-thin) solid var(--color-accent); }
.timeline-rail__item[data-state="done"]::before { background-color: var(--color-accent); }
.timeline-rail__time {
  display: block;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: var(--color-ink-muted);
  margin-bottom: var(--space-1);
}
.timeline-rail__body { color: var(--color-ink-soft); }

/* 左侧索引脉络 */
.index-rail { position: relative; }
.index-rail__group {
  padding-block: var(--space-2);
  border-top: var(--border-thin) solid var(--color-line);
}
.index-rail__head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: var(--color-ink);
}
.index-rail__count { color: var(--color-ink-muted); }
.index-rail__list { margin-top: var(--space-1); }
.index-rail__link {
  display: block;
  padding: var(--space-1) 0 var(--space-1) var(--space-2);
  border-left: var(--border-thick) solid transparent;
  font-size: var(--text-sm);
  color: var(--color-ink-soft);
  transition: border-color 0.14s linear, color 0.14s linear, padding-left 0.14s linear;
}
.index-rail__link:hover, .index-rail__link:focus-visible { color: var(--color-primary); border-left-color: var(--color-primary); }
.index-rail__item.is-current .index-rail__link {
  color: var(--color-primary);
  border-left-color: var(--color-primary);
  padding-left: var(--space-3);
  background-color: var(--color-primary-soft);
}

/* 深色面板 */
.panel-dark {
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  padding-block: var(--section-y-lg);
}
.panel-dark a { color: var(--color-contrast-accent); }
.panel-dark .rule { border-top-color: var(--color-contrast-line); }
.panel-dark .tag {
  background-color: transparent;
  border-color: var(--color-contrast-line);
  color: var(--color-contrast-accent);
}
.panel-dark p { color: color-mix(in srgb, var(--color-contrast-ink) 78%, var(--color-contrast-surface)); }

/* 正文 */
.article { max-width: var(--measure); }
.article > * + * { margin-top: var(--space-3); }
.article h2 {
  font-size: var(--text-xl);
  padding-left: var(--space-3);
  border-left: var(--border-thick) solid var(--color-primary);
  margin-top: var(--space-6);
}
.article h3 {
  font-family: var(--font-body);
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  margin-top: var(--space-4);
}
.article p { color: var(--color-ink); }
.article ul, .article ol { display: grid; gap: var(--space-1); }
.article li {
  position: relative;
  padding-left: var(--space-4);
  color: var(--color-ink-soft);
}
.article li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.78em;
  width: var(--space-2);
  height: var(--border-thin);
  background-color: var(--color-ink-muted);
}
.article blockquote {
  padding: var(--space-3) var(--space-4);
  border-left: var(--border-thick) solid var(--color-accent);
  background-color: var(--color-surface-alt);
  color: var(--color-ink-soft);
}
.panel-dark .article p,
.panel-dark .article li { color: color-mix(in srgb, var(--color-contrast-ink) 82%, var(--color-contrast-surface)); }

/* 滚动显现 */
.has-js [data-observe] {
  opacity: 0;
  transform: translateY(7px);
  transition: opacity 0.32s linear, transform 0.32s linear;
}
.has-js [data-observe].is-visible { opacity: 1; transform: none; }

/* ============================================================
   9. 动效降级
   ============================================================ */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    transition-duration: 0.001ms !important;
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
  }
  html { scroll-behavior: auto !important; }
  .has-js [data-observe] { opacity: 1 !important; transform: none !important; }
  .skip-link { transition: none; }
}