/* =========================================================
   米兰赛场 · 共享样式 /assets/site.css
   展览画册式布局 + 赛场实况节奏
   ========================================================= */

/* ---------- 1. Reset ---------- */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-padding-top: calc(var(--hdr-bar) + 52px); }
body, h1, h2, h3, h4, p, figure, blockquote, dl, dd { margin: 0; }
ul, ol { margin: 0; padding: 0; }
img, svg { display: block; max-width: 100%; }
button { font: inherit; color: inherit; }
a { color: inherit; }

/* ---------- 2. 变量 ---------- */
:root {
  /* 色板 */
  --red: #C8102E;
  --red-deep: #7A0C1C;
  --ink: #0B0B0C;
  --carbon: #1C1D21;
  --paper: #F6F7F4;
  --blue: #1E5FA8;
  --jade: #0F8A6A;
  --gold: #D4A017;
  --mist: #8A8F98;
  --line: #D9DDE3;
  --line-ink: rgba(246, 247, 244, 0.16);
  --ink-70: rgba(246, 247, 244, 0.7);

  /* 阴影：极细边界 + 微阴影 */
  --shadow-1: 0 1px 0 rgba(11, 11, 12, 0.05), 0 10px 26px -22px rgba(11, 11, 12, 0.45);
  --shadow-2: 0 2px 0 rgba(11, 11, 12, 0.07), 0 26px 52px -34px rgba(11, 11, 12, 0.6);

  /* 字体 */
  --font-display: "Source Han Sans SC", "Noto Sans SC", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", system-ui, -apple-system, sans-serif;
  --font-body: var(--font-display);
  --font-mono: "Roboto Mono", "IBM Plex Mono", ui-monospace, SFMono-Regular, Menlo, Consolas, "Noto Sans Mono CJK SC", monospace;

  /* 尺度 */
  --shell: 1240px;
  --gutter: clamp(18px, 4vw, 48px);
  --hdr-bar: 74px;
  --announce-h: 32px;
  --r: 2px;
  --ease: cubic-bezier(0.22, 0.61, 0.36, 1);
}

@media (prefers-reduced-motion: no-preference) {
  html:focus-within { scroll-behavior: smooth; }
}

/* ---------- 3. 中文排版基底 ---------- */
body {
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.85;
  font-weight: 400;
  letter-spacing: 0.01em;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}
@media (min-width: 900px) {
  body { font-size: 17px; }
}
h1, h2, h3, h4 { line-height: 1.25; font-weight: 800; letter-spacing: -0.005em; }
h1 { font-size: clamp(34px, 5.4vw, 68px); }
h2 { font-size: clamp(24px, 3.2vw, 38px); }
h3 { font-size: clamp(18px, 2vw, 22px); }
strong { font-weight: 800; }

/* ---------- 4. 焦点与无障碍 ---------- */
:focus-visible {
  outline: 2px solid var(--red);
  outline-offset: 3px;
  border-radius: var(--r);
}
.site-header :focus-visible,
.site-footer :focus-visible {
  outline-color: var(--gold);
}
.visually-hidden {
  position: absolute; width: 1px; height: 1px; overflow: hidden;
  clip: rect(0 0 0 0); clip-path: inset(50%); white-space: nowrap;
}
.skip-link {
  position: absolute; top: -70px; left: 16px; z-index: 200;
  display: inline-block; padding: 11px 18px;
  background: var(--red); color: #fff; text-decoration: none;
  font-family: var(--font-mono); font-size: 13px; font-weight: 600; letter-spacing: 0.06em;
  border-radius: var(--r);
  transition: top 140ms var(--ease);
}
.skip-link:focus { top: 14px; }

/* ---------- 5. 布局容器 ---------- */
.shell {
  width: 100%;
  max-width: var(--shell);
  margin-inline: auto;
  padding-inline: var(--gutter);
}
.header-spacer { height: calc(var(--hdr-bar) + var(--announce-h)); }

.section { padding: clamp(46px, 7vw, 104px) 0; }
.section--tight { padding: clamp(28px, 4vw, 56px) 0; }
.section--paper { background: var(--paper); color: var(--ink); }
.section--ink { background: var(--ink); color: var(--paper); }
.section--carbon { background: var(--carbon); color: var(--paper); }

.section__head {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 34ch);
  gap: clamp(18px, 3vw, 48px);
  align-items: end;
  margin-bottom: clamp(24px, 3.4vw, 48px);
}
.section__title { margin-top: 14px; }
.section__note { color: var(--mist); font-size: 14.5px; line-height: 1.8; }
.section--ink .section__note,
.section--carbon .section__note { color: var(--ink-70); }
.section__more { margin-top: clamp(20px, 3vw, 36px); }
.eyebrow {
  display: inline-flex; align-items: center; gap: 10px;
  font-family: var(--font-mono); font-size: 11px; font-weight: 600;
  letter-spacing: 0.2em; text-transform: uppercase;
  color: var(--red);
}
.eyebrow::before { content: ""; width: 22px; height: 2px; background: var(--red); flex: none; }
.section--ink .eyebrow,
.section--carbon .eyebrow { color: var(--gold); }
.section--ink .eyebrow::before,
.section--carbon .eyebrow::before { background: var(--gold); }

/* ---------- 6. 头部 ---------- */
.site-header {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 90;
  color: var(--paper);
  background: linear-gradient(180deg, rgba(11, 11, 12, 0.78) 0%, rgba(11, 11, 12, 0.3) 60%, rgba(11, 11, 12, 0) 100%);
  transition: background-color 120ms linear, box-shadow 120ms linear;
}
.site-header.is-solid {
  background: var(--ink);
  box-shadow: 0 1px 0 var(--red), 0 18px 34px -30px rgba(0, 0, 0, 0.95);
}

.announce {
  display: flex;
  align-items: center;
  gap: 10px;
  min-height: var(--announce-h);
  padding: 0 var(--gutter);
  background: var(--red);
  color: #fff;
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.05em;
}
.announce__dot {
  width: 6px; height: 6px; flex: none;
  border-radius: 50%;
  background: #fff;
  box-shadow: 0 0 0 3px rgba(255, 255, 255, 0.28);
  animation: announcePulse 2.6s var(--ease) infinite;
}
.announce__text {
  flex: 1 1 auto;
  min-width: 0;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.announce__link {
  flex: none;
  color: #fff;
  text-decoration: none;
  border-bottom: 1px solid rgba(255, 255, 255, 0.55);
  white-space: nowrap;
  transition: border-color 120ms linear;
}
.announce__link:hover { border-bottom-color: #fff; }
@keyframes announcePulse {
  0%, 100% { box-shadow: 0 0 0 3px rgba(255, 255, 255, 0.28); }
  50% { box-shadow: 0 0 0 8px rgba(255, 255, 255, 0); }
}

.site-header__bar { position: relative; }
.site-header__inner {
  display: flex;
  align-items: center;
  gap: clamp(10px, 2vw, 28px);
  min-height: var(--hdr-bar);
}

/* 品牌 */
.brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  flex: none;
  color: inherit;
  text-decoration: none;
}
.brand__mark {
  display: grid;
  place-items: center;
  width: 44px; height: 36px;
  background: var(--red);
  color: #fff;
  font-family: var(--font-mono);
  font-size: 14px;
  font-weight: 600;
  letter-spacing: 0.06em;
  clip-path: polygon(14% 0, 100% 0, 86% 100%, 0 100%);
}
.brand__text { display: flex; flex-direction: column; line-height: 1.15; }
.brand__name { font-family: var(--font-display); font-size: 18px; font-weight: 800; letter-spacing: 0.02em; }
.brand__note {
  margin-top: 3px;
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.16em;
  color: var(--mist);
}

/* 主导航：桌面横向滚动 */
.site-nav {
  flex: 1 1 auto;
  min-width: 0;
  overflow-x: auto;
  overscroll-behavior-x: contain;
  scrollbar-width: none;
}
.site-nav::-webkit-scrollbar { display: none; }
.site-nav__list {
  display: flex;
  align-items: center;
  gap: clamp(4px, 1.4vw, 22px);
  list-style: none;
}
.site-nav__item { flex: none; }
.site-nav__link {
  position: relative;
  display: inline-flex;
  align-items: baseline;
  gap: 7px;
  padding: 12px 2px;
  color: inherit;
  text-decoration: none;
  font-size: 15px;
  font-weight: 600;
  white-space: nowrap;
  opacity: 0.8;
  transition: opacity 120ms linear, color 120ms linear;
}
.site-nav__link::after {
  content: "";
  position: absolute;
  left: 0; right: 0; bottom: 5px;
  height: 2px;
  background: var(--red);
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform 180ms var(--ease);
}
.site-nav__link:hover { opacity: 1; }
.site-nav__link:hover::after { transform: scaleX(1); }
.site-nav__idx {
  font-family: var(--font-mono);
  font-size: 10.5px;
  letter-spacing: 0.08em;
  color: var(--mist);
}
.site-nav__link[aria-current="page"] { opacity: 1; }
.site-nav__link[aria-current="page"]::after { transform: scaleX(1); }
.site-nav__link[aria-current="page"] .site-nav__idx { color: var(--gold); }

.site-header__acts {
  display: flex;
  align-items: center;
  gap: 10px;
  flex: none;
  margin-left: auto;
}

/* 移动导航按钮 */
.nav-toggle {
  display: none;
  align-items: center;
  gap: 9px;
  padding: 9px 12px;
  background: rgba(246, 247, 244, 0.04);
  border: 1px solid rgba(246, 247, 244, 0.32);
  border-radius: var(--r);
  color: inherit;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  cursor: pointer;
  transition: background-color 140ms var(--ease), border-color 140ms var(--ease);
}
.nav-toggle:hover { background: rgba(246, 247, 244, 0.1); border-color: var(--paper); }
.nav-toggle__box { display: flex; flex-direction: column; gap: 4px; width: 16px; flex: none; }
.nav-toggle__bar {
  display: block;
  height: 2px;
  background: currentColor;
  transition: transform 180ms var(--ease), opacity 140ms linear;
}
.site-header[data-open] .nav-toggle__bar:nth-child(1) { transform: translateY(6px) rotate(45deg); }
.site-header[data-open] .nav-toggle__bar:nth-child(2) { opacity: 0; }
.site-header[data-open] .nav-toggle__bar:nth-child(3) { transform: translateY(-6px) rotate(-45deg); }
.nav-toggle__label { white-space: nowrap; }

/* 滚动进度 */
.scroll-progress {
  position: absolute;
  left: 0; bottom: 0;
  height: 2px;
  width: 0;
  background: linear-gradient(90deg, var(--red) 0%, var(--gold) 100%);
  pointer-events: none;
  transition: width 90ms linear;
}

/* ---------- 7. 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 11px 18px;
  border: 1px solid transparent;
  border-radius: var(--r);
  font-family: var(--font-mono);
  font-size: 12.5px;
  font-weight: 600;
  letter-spacing: 0.06em;
  line-height: 1;
  text-decoration: none;
  cursor: pointer;
  background: none;
  transition: background-color 140ms var(--ease), color 140ms var(--ease),
              border-color 140ms var(--ease), transform 140ms var(--ease);
}
.btn:hover { transform: translateY(-1px); }
.btn:active { transform: translateY(0); }
.btn--sm { padding: 9px 14px; font-size: 12px; }
.btn--solid { background: var(--red); color: #fff; }
.btn--solid:hover { background: var(--red-deep); }
.btn--line {
  border-color: rgba(246, 247, 244, 0.32);
  background: rgba(246, 247, 244, 0.04);
  color: var(--paper);
}
.btn--line:hover { border-color: var(--paper); background: rgba(246, 247, 244, 0.12); }
.btn--ink { background: var(--ink); color: var(--paper); }
.btn--ink:hover { background: var(--carbon); }
.btn--ghost { border-color: var(--line); color: var(--ink); background: transparent; }
.btn--ghost:hover { border-color: var(--ink); }

/* ---------- 8. 页脚 ---------- */
.site-footer {
  position: relative;
  margin-top: clamp(56px, 9vw, 120px);
  background: var(--ink);
  color: var(--paper);
  overflow: hidden;
}
.site-footer::before {
  content: "";
  position: absolute;
  inset: 0;
  background: radial-gradient(120% 82% at 100% 0%, rgba(200, 16, 46, 0.16) 0%, rgba(11, 11, 12, 0) 62%);
  pointer-events: none;
}
.site-footer__wedge {
  position: absolute;
  top: 0; left: 0;
  width: min(320px, 56vw);
  height: 6px;
  background: var(--red);
  clip-path: polygon(0 0, 100% 0, calc(100% - 44px) 100%, 0 100%);
}
.site-footer__inner { position: relative; z-index: 1; }

.site-footer__grid {
  display: grid;
  grid-template-columns: minmax(0, 1.3fr) repeat(3, minmax(0, 1fr));
  gap: clamp(26px, 3.4vw, 56px);
  padding: clamp(46px, 6vw, 84px) 0 clamp(26px, 3vw, 40px);
}
.footer-lead { display: flex; flex-direction: column; gap: 16px; max-width: 46ch; }
.brand--footer .brand__name { font-size: 20px; }
.brand--footer .brand__note { color: rgba(246, 247, 244, 0.45); }
.footer-lead__text { color: var(--ink-70); font-size: 14.5px; line-height: 1.85; }
.footer-lead__addr {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.05em;
  color: var(--mist);
}

.footer-col__title {
  display: flex;
  align-items: center;
  gap: 9px;
  margin-bottom: 16px;
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--paper);
}
.footer-col__title::before { content: ""; width: 14px; height: 2px; background: var(--red); flex: none; }
.footer-col__list { list-style: none; display: flex; flex-direction: column; gap: 11px; }
.footer-link {
  position: relative;
  display: inline-block;
  color: var(--ink-70);
  text-decoration: none;
  font-size: 14.5px;
  transition: color 120ms linear;
}
a.footer-link::after {
  content: "";
  position: absolute;
  left: 0; right: 100%; bottom: -2px;
  height: 1px;
  background: var(--red);
  transition: right 200ms var(--ease);
}
a.footer-link:hover { color: var(--paper); }
a.footer-link:hover::after { right: 0; }
.footer-link--data {
  font-family: var(--font-mono);
  font-size: 12.5px;
  letter-spacing: 0.02em;
  color: rgba(246, 247, 244, 0.5);
  word-break: break-all;
}

.site-footer__base {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 14px 26px;
  padding: 22px 0 30px;
  border-top: 1px solid var(--line-ink);
}
.footer-legal { display: flex; flex-wrap: wrap; gap: 8px 22px; list-style: none; }
.footer-legal a {
  color: var(--ink-70);
  text-decoration: none;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  transition: color 120ms linear;
}
.footer-legal a:hover { color: var(--gold); }
.footer-reg {
  flex: 1 1 320px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.04em;
  color: var(--mist);
}

/* 返回顶部 */
.to-top {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  padding: 12px 16px;
  border: 1px solid var(--line-ink);
  border-radius: var(--r);
  background: var(--carbon);
  color: var(--paper);
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.12em;
  cursor: pointer;
  transition: background-color 140ms var(--ease), border-color 140ms var(--ease);
}
.to-top:hover { background: var(--red); border-color: var(--red); }
.to-top__arrow { font-size: 14px; line-height: 1; }
.to-top--float {
  position: fixed;
  right: clamp(16px, 3vw, 34px);
  bottom: clamp(18px, 4vw, 34px);
  z-index: 70;
  box-shadow: 0 18px 40px -26px rgba(0, 0, 0, 0.9);
  opacity: 0;
  visibility: hidden;
  transform: translateY(12px);
  transition: opacity 180ms var(--ease), transform 180ms var(--ease),
              visibility 0s linear 200ms, background-color 140ms var(--ease), border-color 140ms var(--ease);
}
.to-top--float.is-visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
  transition-delay: 0s, 0s, 0s, 0s;
}

/* ---------- 9. 网格 ---------- */
.grid { display: grid; gap: clamp(16px, 2.2vw, 28px); }
.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--sidebar { grid-template-columns: minmax(0, 1fr) minmax(240px, 300px); }
.grid--index { gap: 0; }

/* ---------- 10. 卡片 ---------- */
.card {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 12px;
  padding: clamp(18px, 2.2vw, 26px);
  background: #fff;
  border: 1px solid var(--line);
  border-radius: var(--r);
  box-shadow: var(--shadow-1);
  transition: border-color 140ms var(--ease), transform 140ms var(--ease), box-shadow 140ms var(--ease);
}
.card:hover { border-color: var(--ink); transform: translateY(-3px); box-shadow: var(--shadow-2); }
.card__index { font-family: var(--font-mono); font-size: 11px; letter-spacing: 0.16em; color: var(--red); }
.card__title { font-size: 19px; font-weight: 800; line-height: 1.4; }
.card__body { font-size: 15px; line-height: 1.8; color: #3C3F45; }
.card__meta {
  margin-top: auto;
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.06em;
  color: var(--mist);
}
.card--ink { background: var(--carbon); border-color: rgba(246, 247, 244, 0.12); color: var(--paper); }
.card--ink:hover { border-color: var(--red); }
.card--ink .card__body { color: var(--ink-70); }

/* ---------- 11. 图片容器 ---------- */
.media { position: relative; display: block; }
.media__frame {
  position: relative;
  overflow: hidden;
  aspect-ratio: 16 / 10;
  background: var(--carbon);
  border: 1px solid var(--line);
  border-radius: var(--r);
}
.media__img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 600ms var(--ease);
}
.media:hover .media__img { transform: scale(1.03); }
.media--tall .media__frame { aspect-ratio: 3 / 4; }
.media--wide .media__frame { aspect-ratio: 21 / 9; }
.media--square .media__frame { aspect-ratio: 1 / 1; }
.media--cut .media__frame {
  border: 0;
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 48px), calc(100% - 48px) 100%, 0 100%);
}
.media__frame--ph {
  display: grid;
  place-items: center;
  border-style: dashed;
  color: rgba(246, 247, 244, 0.42);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  background-image: repeating-linear-gradient(-45deg, rgba(246, 247, 244, 0.05) 0 2px, transparent 2px 12px);
}
.media__caption {
  margin-top: 10px;
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.04em;
  color: var(--mist);
}

/* ---------- 12. 数据与标签 ---------- */
.stat { display: flex; flex-direction: column; gap: 6px; }
.stat__value {
  font-family: var(--font-mono);
  font-weight: 600;
  font-size: clamp(28px, 4vw, 48px);
  line-height: 1;
  letter-spacing: -0.02em;
  color: var(--ink);
}
.stat__value--gold { color: var(--gold); }
.stat__value--jade { color: var(--jade); }
.stat__value--red { color: var(--red); }
.stat__label {
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--mist);
}
.section--ink .stat__value,
.section--carbon .stat__value { color: var(--paper); }

.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 9px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: #fff;
  color: #4A4E56;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.06em;
}
.tag--red { border-color: rgba(200, 16, 46, 0.35); color: var(--red); background: rgba(200, 16, 46, 0.06); }
.tag--blue { border-color: rgba(30, 95, 168, 0.35); color: var(--blue); background: rgba(30, 95, 168, 0.06); }
.tag--jade { border-color: rgba(15, 138, 106, 0.35); color: var(--jade); background: rgba(15, 138, 106, 0.07); }
.tag--gold { border-color: rgba(212, 160, 23, 0.42); color: #8A6A06; background: rgba(212, 160, 23, 0.12); }
.tag--mist { color: var(--mist); }

/* ---------- 13. 高密度索引 ---------- */
.index-list { list-style: none; border-top: 1px solid var(--line); }
.index-list__item {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr) auto;
  gap: 14px;
  align-items: center;
  padding: 14px 0;
  border-bottom: 1px solid var(--line);
  transition: background-color 140ms var(--ease);
}
.index-list__item:hover { background: rgba(11, 11, 12, 0.03); }
.index-list__rank { font-family: var(--font-mono); font-size: 12px; letter-spacing: 0.08em; color: var(--red); }
.index-list__label { font-size: 15.5px; font-weight: 600; }
.index-list__value { font-family: var(--font-mono); font-size: 13px; letter-spacing: 0.04em; color: var(--mist); }
.index-list__value--up { color: var(--jade); }
.index-list__value--down { color: var(--red); }

/* ---------- 14. 正文与旁注 ---------- */
.prose { max-width: 68ch; }
.prose h2 { margin: 2.2em 0 0.7em; }
.prose h3 { margin: 1.8em 0 0.6em; }
.prose p { margin-bottom: 1.2em; }
.prose ul, .prose ol { margin: 0 0 1.2em; padding-left: 1.3em; }
.prose li { margin: 0.35em 0; }
.prose a { color: var(--blue); text-decoration: none; border-bottom: 1px solid rgba(30, 95, 168, 0.35); }
.prose a:hover { border-bottom-color: var(--blue); }
.prose code {
  font-family: var(--font-mono);
  font-size: 0.9em;
  padding: 2px 6px;
  background: rgba(11, 11, 12, 0.06);
  border-radius: var(--r);
}
.prose blockquote {
  margin: 0 0 1.2em;
  padding: 6px 0 6px 18px;
  border-left: 2px solid var(--red);
  color: #3C3F45;
}
.note {
  border-left: 2px solid var(--red);
  padding: 4px 0 4px 14px;
  color: var(--mist);
  font-size: 14px;
  line-height: 1.8;
}
.note--blue { border-left-color: var(--blue); }

/* ---------- 15. 面包屑与链接 ---------- */
.breadcrumb { padding: 14px 0; }
.breadcrumb__list {
  display: flex;
  flex-wrap: wrap;
  gap: 6px 10px;
  list-style: none;
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.06em;
  color: var(--mist);
}
.breadcrumb__item { display: flex; align-items: center; gap: 10px; }
.breadcrumb__item + .breadcrumb__item::before { content: "/"; color: var(--line); }
.breadcrumb__link { color: var(--mist); text-decoration: none; transition: color 120ms linear; }
.breadcrumb__link:hover { color: var(--red); }
.breadcrumb__item[aria-current="page"] { color: var(--ink); }

.link-arrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  color: var(--red);
  text-decoration: none;
  font-family: var(--font-mono);
  font-size: 12.5px;
  font-weight: 600;
  letter-spacing: 0.06em;
  border-bottom: 1px solid transparent;
  transition: border-color 140ms var(--ease), gap 140ms var(--ease);
}
.link-arrow::after { content: "→"; }
.link-arrow:hover { border-bottom-color: var(--red); gap: 12px; }

.divider { height: 1px; border: 0; margin: clamp(28px, 4vw, 56px) 0; background: var(--line); }
.divider--ink { background: var(--line-ink); }

/* ---------- 16. 章节目录跟随 ---------- */
.chapter-nav {
  position: sticky;
  top: calc(var(--hdr-bar) + 58px);
  align-self: start;
}
.chapter-nav__title {
  margin-bottom: 12px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--mist);
}
.chapter-nav__list { list-style: none; display: flex; flex-direction: column; }
.chapter-nav__link {
  display: flex;
  align-items: baseline;
  gap: 10px;
  padding: 9px 0 9px 12px;
  border-left: 2px solid var(--line);
  color: #4A4E56;
  text-decoration: none;
  font-size: 14px;
  transition: color 140ms linear, border-color 140ms linear, background-color 140ms linear;
}
.chapter-nav__link:hover { color: var(--ink); border-left-color: var(--mist); }
.chapter-nav__link.is-active {
  color: var(--ink);
  border-left-color: var(--red);
  background: rgba(200, 16, 46, 0.05);
  font-weight: 700;
}
.chapter-nav__idx { font-family: var(--font-mono); font-size: 11px; color: var(--mist); }

/* ---------- 17. 显现 ---------- */
.reveal {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity 520ms var(--ease), transform 520ms var(--ease);
}
.reveal.is-visible { opacity: 1; transform: none; }

/* ---------- 18. 工具类 ---------- */
.u-mono { font-family: var(--font-mono); letter-spacing: 0.06em; }
.u-center { text-align: center; }
.u-muted { color: var(--mist); }
.u-ink { color: var(--ink); }
.u-hairline { border-top: 1px solid var(--line); }
.u-block { display: block; }

/* ---------- 19. 响应式 ---------- */
@media (max-width: 1080px) {
  .site-header__acts .btn--line { display: none; }
}
@media (max-width: 1020px) {
  .grid--4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .grid--3 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .grid--sidebar { grid-template-columns: minmax(0, 1fr); }
  .chapter-nav { position: static; }
  .site-footer__grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .footer-lead { grid-column: 1 / -1; }
}
@media (max-width: 980px) {
  .nav-toggle { display: inline-flex; }

  .site-nav {
    position: absolute;
    left: 0; right: 0;
    top: 100%;
    display: block;
    overflow: hidden;
    max-height: 0;
    opacity: 0;
    visibility: hidden;
    background: var(--ink);
    border-top: 1px solid var(--line-ink);
    box-shadow: 0 26px 48px -30px rgba(0, 0, 0, 0.95);
    transition: max-height 260ms var(--ease), opacity 160ms linear, visibility 0s linear 260ms;
  }
  .site-header[data-open] .site-nav,
  .site-nav[data-open] {
    max-height: min(70vh, 520px);
    overflow-y: auto;
    opacity: 1;
    visibility: visible;
    transition: max-height 300ms var(--ease), opacity 160ms linear;
  }
  .site-nav__list {
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding: 6px 0 18px;
  }
  .site-nav__item { border-bottom: 1px solid var(--line-ink); }
  .site-nav__item:last-child { border-bottom: 0; }
  .site-nav__link {
    width: 100%;
    padding: 16px var(--gutter);
    font-size: 17px;
    opacity: 1;
  }
  .site-nav__link::after {
    left: var(--gutter);
    right: auto;
    width: 24px;
    bottom: 12px;
  }
  .site-nav__idx { font-size: 11.5px; }
}
@media (max-width: 820px) {
  .section__head { grid-template-columns: minmax(0, 1fr); align-items: start; }
}
@media (max-width: 760px) {
  .grid--2, .grid--3, .grid--4 { grid-template-columns: minmax(0, 1fr); }
  .index-list__item { grid-template-columns: auto minmax(0, 1fr); }
  .index-list__item .index-list__value { grid-column: 2; justify-self: start; }
}
@media (max-width: 620px) {
  .site-footer__grid { grid-template-columns: minmax(0, 1fr); }
}
@media (max-width: 560px) {
  .site-header__acts .btn--solid { display: none; }
  .brand__note { display: none; }
  .announce { font-size: 11px; }
  .announce__link { display: none; }
  .to-top--float { padding: 11px 13px; }
  .to-top--float .to-top__label { display: none; }
}

/* ---------- 20. 动效降级 ---------- */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
    scroll-behavior: auto !important;
  }
  .reveal { opacity: 1; transform: none; }
  .scroll-progress { transition: none; }
  .site-nav__link::after { transform: scaleX(1); }
}