:root {
  --color-surface: #edeeed;
  --color-surface-alt: #e4e6e4;
  --color-surface-deep: #d8dad8;
  --color-ink: #3a453c;
  --color-ink-soft: #5c6b5e;
  --color-ink-muted: #778879;
  --color-line: #cdd0cd;
  --color-primary: #278632;
  --color-primary-ink: #ffffff;
  --color-primary-soft: #d1dfd3;
  --color-accent: #9b25da;
  --color-accent-ink: #ffffff;
  --color-highlight: #decaea;
  --color-focus: #9e18e7;
  --color-contrast-surface: #1b2c1d;
  --color-contrast-ink: #e4e7e5;
  --color-contrast-line: #475549;
  --color-contrast-accent: #bd6fe7;
  --overlay-scrim: linear-gradient(180deg, rgba(27, 44, 29, 0.35) 0%, rgba(27, 44, 29, 0.72) 55%, rgba(27, 44, 29, 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: 12.2px;
  --text-sm: 15.2px;
  --text-base: 17px;
  --text-lg: 21.2px;
  --text-xl: 26.6px;
  --text-2xl: 33.2px;
  --text-3xl: 41.5px;
  --text-4xl: 51.9px;
  --text-display: clamp(43px, 8.8vw, 113px);
  --text-figure: clamp(36px, 6.3vw, 81px);
  --weight-heading: 787;
  --weight-body: 400;
  --leading-body: 1.79;
  --leading-heading: 1.16;
  --tracking-heading: 0.002em;
  --radius-sm: 0px;
  --radius-md: 2px;
  --radius-lg: 3px;
  --radius-pill: 3px;
  --border-thin: 1px;
  --border-thick: 1px;
  --shadow-1: 0 1px 0 rgba(58, 69, 60, 0.12);
  --shadow-2: 0 2px 0 rgba(58, 69, 60, 0.18);
  --space-1: 7px;
  --space-2: 14px;
  --space-3: 21px;
  --space-4: 28px;
  --space-6: 42px;
  --space-8: 56px;
  --container: 1240px;
  --measure: 71ch;
  --gutter: 21px;
  --section-y: 95px;
  --section-y-lg: 133px;
}

/* ============ RESET ============ */
*,
*::before,
*::after { box-sizing: border-box; }

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}

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;
  overflow-x: hidden;
}

h1, h2, h3, h4, h5, h6 {
  margin: 0 0 var(--space-2);
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
}

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%; height: auto; }

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

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

hr { height: 0; border: 0; border-top: var(--border-thin) solid var(--color-line); margin: var(--space-6) 0; }

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

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

/* ============ 中文排版与工具类 ============ */
.mono,
.annotation,
.meta {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: var(--text-xs);
  line-height: 1.55;
  letter-spacing: 0.06em;
  color: var(--color-ink-muted);
}

.annotation { display: block; }
.annotation--inline { display: inline-block; }

.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;
}

.container {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--space-4);
}

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

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

.span-1 { grid-column: span 1; }
.span-2 { grid-column: span 2; }
.span-3 { grid-column: span 3; }
.span-4 { grid-column: span 4; }
.span-5 { grid-column: span 5; }
.span-6 { grid-column: span 6; }
.span-7 { grid-column: span 7; }
.span-8 { grid-column: span 8; }
.span-9 { grid-column: span 9; }
.span-10 { grid-column: span 10; }
.span-11 { grid-column: span 11; }
.span-12 { grid-column: span 12; }

/* ============ 页头：左侧固定轨道 ============ */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  z-index: 100;
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
  width: 244px;
  padding: var(--space-4) var(--space-3);
  background-color: var(--color-surface-alt);
  border-right: var(--border-thin) solid var(--color-line);
}

.read-progress {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 130;
  height: 2px;
  background-color: var(--color-line);
}

.read-progress > span {
  display: block;
  width: 0;
  height: 100%;
  background-color: var(--color-accent);
  transition: width 0.12s linear;
}

.skip-link {
  position: fixed;
  top: var(--space-2);
  left: var(--space-2);
  z-index: 200;
  transform: translateY(-220%);
  padding: var(--space-2) var(--space-3);
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border: var(--border-thin) solid var(--color-contrast-line);
  border-radius: var(--radius-md);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  transition: transform 0.18s ease;
}

.skip-link:focus { transform: translateY(0); }

.topbar {
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
}

.brand {
  display: block;
  padding-bottom: var(--space-3);
  color: var(--color-ink);
  border-bottom: var(--border-thin) solid var(--color-line);
}

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

.brand__cn {
  display: block;
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-xl);
  line-height: 1.05;
  letter-spacing: 0.01em;
}

.brand__en {
  display: block;
  margin-top: var(--space-1);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
  color: var(--color-ink-muted);
}

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

.nav-toggle {
  display: none;
  align-items: center;
  gap: var(--space-1);
  padding: var(--space-1) var(--space-2);
  background-color: var(--color-surface);
  color: var(--color-ink);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-md);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
}

.nav-toggle__box {
  position: relative;
  display: inline-block;
  width: 18px;
  height: 12px;
}

.nav-toggle__box span {
  position: absolute;
  left: 0;
  width: 100%;
  height: 2px;
  background-color: currentColor;
  transition: transform 0.2s ease;
}

.nav-toggle__box span:first-child { top: 0; }
.nav-toggle__box span:last-child { bottom: 0; }

.nav-toggle[aria-expanded="true"] .nav-toggle__box span:first-child { transform: translateY(5px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] .nav-toggle__box span:last-child { transform: translateY(-5px) rotate(-45deg); }

/* ============ 轨道导航 ============ */
.rail {
  display: flex;
  flex: 1 1 auto;
  flex-direction: column;
  gap: var(--space-3);
  min-height: 0;
  margin-top: var(--space-1);
}

.rail__list {
  display: flex;
  flex-direction: column;
  min-height: 0;
  padding-block: var(--space-2);
  overflow-y: auto;
  border-top: var(--border-thin) solid var(--color-line);
  border-bottom: var(--border-thin) solid var(--color-line);
}

.rail__link {
  display: grid;
  grid-template-columns: 2.2em 1fr;
  align-items: baseline;
  gap: var(--space-1);
  padding: var(--space-2) var(--space-2) var(--space-2) var(--space-2);
  border-left: 4px solid transparent;
  color: var(--color-ink-soft);
  font-size: var(--text-sm);
  line-height: 1.4;
}

.rail__link:hover {
  background-color: var(--color-surface-deep);
  color: var(--color-ink);
  text-decoration: none;
}

.rail__link[aria-current="page"] {
  background-color: var(--color-primary-soft);
  border-left-color: var(--color-primary);
  color: var(--color-ink);
}

.rail__index {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
}

.rail__link[aria-current="page"] .rail__index { color: var(--color-primary); }

.rail__now {
  padding: var(--space-2);
  background-color: var(--color-surface-deep);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-sm);
}

.rail__now-key {
  display: block;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.12em;
  color: var(--color-ink-muted);
}

.rail__now-val {
  display: block;
  margin-top: 3px;
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-sm);
  color: var(--color-ink);
}

.rail__foot {
  margin-top: auto;
  padding-top: var(--space-3);
  border-top: var(--border-thin) solid var(--color-line);
}

.rail__foot-line {
  margin: 0 0 4px;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.03em;
  color: var(--color-ink-muted);
  word-break: break-all;
}

/* ============ 按钮 ============ */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-1);
  padding: var(--space-2) var(--space-3);
  background-color: var(--color-surface);
  color: var(--color-ink);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-md);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.04em;
  text-align: center;
  transition: background-color 0.18s ease, color 0.18s ease, border-color 0.18s ease;
}

.btn:hover {
  background-color: var(--color-surface-deep);
  text-decoration: none;
}

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

.btn--solid:hover {
  background-color: color-mix(in srgb, var(--color-primary) 82%, var(--color-ink));
  border-color: color-mix(in srgb, var(--color-primary) 82%, var(--color-ink));
}

.btn--ghost {
  background-color: transparent;
  color: var(--color-ink-soft);
}

.btn--block { width: 100%; }

.btn--sm {
  padding: var(--space-1) var(--space-2);
  font-size: var(--text-xs);
}

/* ============ 徽标 / 专题色块 ============ */
.badge {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  padding: 2px var(--space-1);
  background-color: var(--color-surface-deep);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-sm);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: var(--color-ink-soft);
}

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

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

.badge--outline { background-color: transparent; }

.section-flag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: var(--space-1) var(--space-3);
  background-color: var(--color-primary);
  color: var(--color-primary-ink);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.18em;
  clip-path: polygon(0 0, 100% 0, calc(100% - 12px) 100%, 0 100%);
}

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

.section-flag--dark {
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
}

.chapter-no {
  display: block;
  margin-bottom: var(--space-2);
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: var(--text-xs);
  letter-spacing: 0.22em;
  color: var(--color-primary);
}

/* ============ 错位分隔 ============ */
.rule-offset {
  width: 68%;
  height: var(--border-thin);
  margin: var(--space-8) 0 var(--space-8) 6%;
  background-color: var(--color-line);
  border: 0;
}

.rule-offset--flip {
  width: 52%;
  margin-left: auto;
  margin-right: 9%;
  background-color: var(--color-primary);
}

/* ============ 图片容器与展签 ============ */
.figure {
  position: relative;
  background-color: var(--color-surface-alt);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-md);
}

.figure__media {
  position: relative;
  overflow: hidden;
  aspect-ratio: 16 / 9;
  background-color: var(--color-surface-deep);
}

.figure__media img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.figure__overlay {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: flex-end;
  padding: var(--space-3);
  background: var(--overlay-scrim);
  color: var(--color-contrast-ink);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  line-height: 1.5;
}

.figure__caption {
  position: absolute;
  left: -1px;
  bottom: -1px;
  z-index: 2;
  padding: 4px var(--space-2);
  background-color: var(--color-surface);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-sm);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.04em;
  color: var(--color-ink-muted);
}

.figure--tall .figure__media { aspect-ratio: 3 / 4; }
.figure--wide .figure__media { aspect-ratio: 21 / 9; }
.figure--square .figure__media { aspect-ratio: 1 / 1; }

/* ============ 图文咬合 ============ */
.collage {
  display: grid;
  grid-template-columns: repeat(12, minmax(0, 1fr));
  gap: var(--gutter);
  align-items: start;
}

.collage__figure {
  grid-column: 1 / span 7;
  grid-row: 1;
}

.collage__text {
  grid-column: 6 / span 7;
  grid-row: 1;
  align-self: end;
  z-index: 2;
  padding: var(--space-3);
  background-color: var(--color-surface);
  border-top: 3px solid var(--color-primary);
  border-radius: var(--radius-md);
}

.collage--tight .collage__text { padding: var(--space-2) var(--space-3); }

/* ============ 面包屑与正文 ============ */
.crumbs {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-1) var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.05em;
  color: var(--color-ink-muted);
}

.crumbs li {
  display: flex;
  align-items: center;
  gap: var(--space-2);
}

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

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

.prose { max-width: var(--measure); }

.prose p,
.prose li { font-size: var(--text-base); }

.prose ul,
.prose ol {
  margin: 0 0 var(--space-4);
  padding-left: 1.5em;
  list-style: disc;
}

.prose ol { list-style: decimal; }
.prose li { margin-bottom: var(--space-1); }
.prose h2 { margin-top: var(--space-6); font-size: var(--text-2xl); }
.prose h3 { margin-top: var(--space-4); font-size: var(--text-lg); }

.prose a {
  color: var(--color-accent);
  border-bottom: var(--border-thin) solid currentColor;
}

.lead {
  max-width: 34ch;
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-xl);
  line-height: 1.35;
  color: var(--color-ink);
}

.dark-panel {
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
}

.dark-panel a { color: var(--color-contrast-accent); }
.dark-panel hr,
.dark-panel .rule-offset { background-color: var(--color-contrast-line); }

/* ============ 数字与动效 ============ */
[data-count] {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  letter-spacing: -0.01em;
}

.figure-type {
  font-family: var(--font-mono);
  font-weight: var(--weight-heading);
  font-size: var(--text-figure);
  line-height: 0.95;
  font-variant-numeric: tabular-nums;
}

@keyframes data-pulse {
  0% { box-shadow: inset 0 0 0 0 var(--color-highlight); }
  34% { box-shadow: inset 0 -0.34em 0 0 var(--color-highlight); }
  100% { box-shadow: inset 0 0 0 0 transparent; }
}

[data-count].is-live { animation: data-pulse 820ms ease-out 1; }

html[data-motion="on"] .reveal {
  opacity: 0;
  transform: translateY(10px);
  transition: opacity 0.5s ease, transform 0.5s ease;
}

html[data-motion="on"] .reveal.is-in {
  opacity: 1;
  transform: none;
}

/* ============ 页脚 ============ */
.site-footer {
  margin-top: var(--section-y-lg);
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-top: var(--border-thin) solid var(--color-contrast-line);
}

.footer__mega {
  position: relative;
  padding: var(--section-y) var(--space-4) var(--space-6);
  border-bottom: var(--border-thin) solid var(--color-contrast-line);
  overflow: hidden;
}

.footer__kicker {
  margin: 0 0 var(--space-3);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.24em;
  color: var(--color-contrast-accent);
}

.footer__word {
  margin: 0;
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-display);
  line-height: 0.95;
  letter-spacing: -0.01em;
  color: var(--color-contrast-ink);
  word-break: keep-all;
}

.footer__line {
  margin: var(--space-4) 0 0;
  max-width: 46ch;
  font-size: var(--text-sm);
  line-height: 1.7;
  color: color-mix(in srgb, var(--color-contrast-ink) 74%, transparent);
}

.footer__cols {
  display: grid;
  grid-template-columns: 1fr 1fr 1.4fr;
  gap: var(--space-6) var(--gutter);
  max-width: var(--container);
  margin-inline: auto;
  padding: var(--space-6) var(--space-4);
}

.footer__h {
  margin: 0 0 var(--space-3);
  font-family: var(--font-mono);
  font-weight: var(--weight-body);
  font-size: var(--text-xs);
  letter-spacing: 0.18em;
  color: var(--color-contrast-accent);
}

.footer__list { display: flex; flex-direction: column; }

.footer__list a {
  display: inline-block;
  padding: 5px 0;
  color: var(--color-contrast-ink);
  font-size: var(--text-sm);
  border-bottom: var(--border-thin) solid transparent;
}

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

.footer__contact {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: var(--space-1) var(--space-2);
  margin: 0 0 var(--space-2);
  font-size: var(--text-sm);
  line-height: 1.6;
}

.footer__contact--text {
  display: block;
  color: color-mix(in srgb, var(--color-contrast-ink) 74%, transparent);
  font-size: var(--text-sm);
}

.footer__strong {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  color: var(--color-contrast-ink);
  word-break: break-all;
}

.copy-btn {
  padding: 2px var(--space-1);
  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;
  color: color-mix(in srgb, var(--color-contrast-ink) 70%, transparent);
  transition: color 0.18s ease, border-color 0.18s ease;
}

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

.copy-btn[data-copied] {
  color: var(--color-contrast-accent);
  border-color: var(--color-contrast-accent);
}

.footer__bottom {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: var(--space-2) var(--space-4);
  max-width: var(--container);
  margin-inline: auto;
  padding: var(--space-3) var(--space-4) var(--space-4);
  border-top: var(--border-thin) solid var(--color-contrast-line);
}

.footer__legal {
  margin: 0;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: color-mix(in srgb, var(--color-contrast-ink) 62%, transparent);
}

/* ============ 桌面主体偏移 ============ */
@media (min-width: 1080px) {
  body { padding-left: 244px; }
}

/* ============ 移动端：顶栏 + 抽屉 ============ */
@media (max-width: 1079px) {
  .site-header {
    position: sticky;
    top: 0;
    left: auto;
    bottom: auto;
    flex-direction: row;
    align-items: center;
    gap: var(--space-2);
    width: 100%;
    padding: var(--space-2) var(--space-3);
    background-color: var(--color-surface);
    border-right: 0;
    border-bottom: var(--border-thin) solid var(--color-line);
  }

  .topbar {
    flex: 1 1 auto;
    flex-direction: row;
    align-items: center;
    justify-content: space-between;
    gap: var(--space-2);
    min-width: 0;
  }

  .brand {
    min-width: 0;
    padding-bottom: 0;
    border-bottom: 0;
  }

  .brand__cn {
    font-size: var(--text-lg);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
  }

  .brand__en { display: none; }

  .topbar__actions {
    flex-direction: row;
    align-items: center;
    flex: 0 0 auto;
  }

  .topbar__cta {
    padding: var(--space-1) var(--space-2);
    font-size: var(--text-xs);
  }

  .nav-toggle { display: inline-flex; }

  body[data-drawer]::after {
    content: "";
    position: fixed;
    inset: 0;
    z-index: 110;
    background-color: color-mix(in srgb, var(--color-contrast-surface) 66%, transparent);
  }

  .rail {
    position: fixed;
    top: 0;
    right: 0;
    bottom: 0;
    z-index: 120;
    width: min(84vw, 340px);
    margin: 0;
    padding: var(--space-6) var(--space-4) var(--space-4);
    gap: var(--space-4);
    background-color: var(--color-contrast-surface);
    color: var(--color-contrast-ink);
    border-left: var(--border-thin) solid var(--color-contrast-line);
    transform: translateX(101%);
    transition: transform 0.26s ease;
    overflow-y: auto;
  }

  .rail[data-open] { transform: translateX(0); }

  .rail__list { border-color: var(--color-contrast-line); }

  .rail__link {
    padding: var(--space-3) var(--space-2);
    border-left-width: 4px;
    color: color-mix(in srgb, var(--color-contrast-ink) 78%, transparent);
    font-size: var(--text-lg);
  }

  .rail__link:hover {
    background-color: color-mix(in srgb, var(--color-contrast-ink) 8%, transparent);
    color: var(--color-contrast-ink);
  }

  .rail__link[aria-current="page"] {
    background-color: color-mix(in srgb, var(--color-primary) 26%, transparent);
    border-left-color: var(--color-primary);
    color: var(--color-contrast-ink);
  }

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

  .rail__now {
    background-color: color-mix(in srgb, var(--color-contrast-ink) 6%, transparent);
    border-color: var(--color-contrast-line);
  }

  .rail__now-key { color: var(--color-contrast-accent); }
  .rail__now-val { color: var(--color-contrast-ink); }

  .rail__foot { border-color: var(--color-contrast-line); }
  .rail__foot-line { color: color-mix(in srgb, var(--color-contrast-ink) 62%, transparent); }
}

/* ============ 平板与手机 ============ */
@media (max-width: 900px) {
  .span-1, .span-2, .span-3, .span-4, .span-5, .span-6,
  .span-7, .span-8, .span-9, .span-10, .span-11, .span-12 { grid-column: span 12; }

  .grid-12 { gap: var(--space-3); }

  .collage__figure,
  .collage__text {
    grid-column: 1 / -1;
    grid-row: auto;
  }

  .collage__text {
    margin-top: calc(var(--space-3) * -1);
    margin-inline: var(--space-2);
  }

  .rule-offset,
  .rule-offset--flip {
    width: 82%;
    margin-left: 0;
    margin-right: auto;
  }

  .footer__cols {
    grid-template-columns: 1fr;
    gap: var(--space-6);
  }

  .footer__bottom { flex-direction: column; }
}

@media (max-width: 540px) {
  .brand__cn { font-size: var(--text-base); }
  .nav-toggle__label { display: none; }
  .footer__mega { padding-top: var(--space-8); }
  .lead { font-size: var(--text-lg); }
}

/* ============ 焦点与减少动效 ============ */
@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;
  }

  html[data-motion="on"] .reveal {
    opacity: 1;
    transform: none;
  }

  .rail { transition: none; }
}