/* ==========================================================================
   爱体育中心 · 球王会官方网站（中文版）
   /assets/site.css — 共享外壳、通用组件与基础排版
   ========================================================================== */

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

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

body,
h1, h2, h3, h4, h5, h6,
p, ol, ul, figure, blockquote, dl, dd, fieldset {
  margin: 0;
}

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

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

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%; }

[hidden] { display: none !important; }

/* ---------- 2. 令牌 ---------- */
:root {
  --ink: #0A1120;
  --panel: #131D31;
  --panel-hi: #1A2740;
  --turf: #1FA45B;
  --lime: #48E08D;
  --red: #E23B3B;
  --red-ink: #FF6B6B;
  --yellow: #F5C518;
  --white: #F2F8FF;
  --grey: #8794A8;

  --line: rgba(255, 255, 255, 0.08);
  --line-soft: rgba(255, 255, 255, 0.05);
  --line-strong: rgba(255, 255, 255, 0.18);

  --rail-w: 88px;
  --topbar-h: 60px;

  --font-sans: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei",
    "Source Han Sans SC", "Noto Sans CJK SC", system-ui, -apple-system,
    "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas,
    "Liberation Mono", "Courier New", monospace;

  --ease: cubic-bezier(0.22, 0.61, 0.36, 1);
}

/* ---------- 3. 页面基调 ---------- */
body {
  background-color: var(--ink);
  color: var(--white);
  font-family: var(--font-sans);
  font-size: 16px;
  font-weight: 400;
  line-height: 1.85;
  min-height: 100vh;
  padding-left: var(--rail-w);
  overflow-x: hidden;
  text-rendering: optimizeLegibility;
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  background-image:
    linear-gradient(rgba(255, 255, 255, 0.022) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255, 255, 255, 0.022) 1px, transparent 1px);
  background-size: 52px 52px;
  pointer-events: none;
  z-index: 0;
}

main {
  position: relative;
  z-index: 1;
  display: block;
}

#main-content { outline: none; }

h1, h2, h3, h4 {
  font-weight: 600;
  line-height: 1.3;
  text-wrap: balance;
}

::selection {
  background: rgba(72, 224, 141, 0.28);
  color: var(--white);
}

:focus-visible {
  outline: 2px solid var(--lime);
  outline-offset: 3px;
}

/* ---------- 4. 跳转链接 ---------- */
.skip-link {
  position: fixed;
  left: 12px;
  top: -140px;
  z-index: 200;
  padding: 11px 18px;
  background: var(--lime);
  color: #06130C;
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.04em;
  transition: top 0.16s var(--ease);
}

.skip-link:focus {
  top: 12px;
}

/* ---------- 5. 左侧数据导航轨 ---------- */
.track-header {
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  width: var(--rail-w);
  z-index: 60;
  display: flex;
  flex-direction: column;
  padding: 20px 0 16px;
  background: linear-gradient(180deg, #0D1729 0%, #0A1120 64%, #0A1120 100%);
  border-right: 1px solid var(--line);
  overflow-y: auto;
  overflow-x: hidden;
  scrollbar-width: none;
}

.track-header::-webkit-scrollbar { display: none; }

.track-header__brand {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
  padding: 0 8px 18px;
  border-bottom: 1px solid var(--line);
  text-align: center;
}

.brand {
  display: block;
  writing-mode: vertical-rl;
  text-orientation: upright;
  font-size: 15px;
  font-weight: 700;
  line-height: 1;
  letter-spacing: 0.14em;
  color: var(--white);
}

.brand:hover { color: var(--lime); }

.brand-sub {
  display: block;
  max-width: 66px;
  font-size: 10px;
  line-height: 1.6;
  letter-spacing: 0.02em;
  color: var(--grey);
  word-break: break-all;
}

/* 移动端菜单按钮（桌面隐藏） */
.nav-toggle { display: none; }

/* 主导航 */
.site-nav {
  display: flex;
  flex-direction: column;
  flex: 1 1 auto;
  min-height: 0;
  padding-top: 14px;
}

.site-nav__title {
  padding-bottom: 10px;
  font-family: var(--font-mono);
  font-size: 9px;
  line-height: 1.4;
  letter-spacing: 0.24em;
  color: var(--grey);
  text-align: center;
  text-transform: uppercase;
}

.site-nav__list {
  display: flex;
  flex-direction: column;
}

.site-nav__item + .site-nav__item {
  border-top: 1px solid var(--line-soft);
}

.site-nav__link {
  display: flex;
  flex-direction: column;
  gap: 5px;
  padding: 11px 6px 11px 8px;
  border-left: 2px solid transparent;
  color: var(--grey);
  transition: color 0.18s var(--ease), border-color 0.18s var(--ease),
    background-color 0.18s var(--ease);
}

.site-nav__link:hover {
  color: var(--white);
  border-left-color: var(--line-strong);
  background: rgba(255, 255, 255, 0.03);
}

.site-nav__link:focus-visible {
  outline: 2px solid var(--lime);
  outline-offset: -2px;
}

.site-nav__link[aria-current="page"] {
  color: var(--white);
  border-left-color: var(--turf);
  background: linear-gradient(90deg, rgba(31, 164, 91, 0.18), rgba(31, 164, 91, 0));
}

.site-nav__idx {
  font-family: var(--font-mono);
  font-size: 9px;
  line-height: 1;
  letter-spacing: 0.16em;
  color: var(--turf);
}

.site-nav__link[aria-current="page"] .site-nav__idx { color: var(--lime); }

.site-nav__label {
  font-size: 12px;
  font-weight: 600;
  line-height: 1.3;
  letter-spacing: 0.01em;
}

/* 轮次切换 */
.round-rail {
  margin-top: auto;
  padding: 16px 8px 4px;
  border-top: 1px solid var(--line);
}

.round-rail__title {
  padding-bottom: 9px;
  font-family: var(--font-mono);
  font-size: 9px;
  line-height: 1.4;
  letter-spacing: 0.24em;
  color: var(--grey);
  text-align: center;
  text-transform: uppercase;
}

.round-rail__chips {
  display: flex;
  flex-direction: column;
  gap: 5px;
}

.chip {
  padding: 7px 4px;
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 500;
  line-height: 1;
  letter-spacing: 0.06em;
  text-align: center;
  color: var(--grey);
  border: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.02);
  transition: color 0.16s var(--ease), border-color 0.16s var(--ease),
    background-color 0.16s var(--ease);
}

.chip:hover {
  color: var(--white);
  border-color: var(--line-strong);
}

.chip:focus-visible {
  outline: 2px solid var(--lime);
  outline-offset: 2px;
}

.chip[aria-pressed="true"] {
  color: #06130C;
  background: var(--lime);
  border-color: var(--lime);
  font-weight: 700;
}

/* 阅读进度 */
.progress-track {
  position: fixed;
  top: 0;
  left: var(--rail-w);
  right: 0;
  height: 3px;
  z-index: 80;
  background: rgba(255, 255, 255, 0.05);
  pointer-events: none;
}

.progress-track__bar {
  display: block;
  width: 0;
  height: 100%;
  background: linear-gradient(90deg, var(--turf) 0%, var(--lime) 68%, var(--yellow) 100%);
}

/* ---------- 6. 页脚 ---------- */
.site-footer {
  position: relative;
  z-index: 1;
  margin-top: 80px;
  padding: 56px 0 28px;
  border-top: 1px solid var(--line);
  background: linear-gradient(180deg, rgba(19, 29, 49, 0) 0%, rgba(19, 29, 49, 0.62) 100%);
}

.site-footer__inner {
  width: min(1160px, 100% - 56px);
  margin-inline: auto;
}

.footer-masthead {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 10px 18px;
  padding-bottom: 26px;
  border-bottom: 1px solid var(--line);
}

.footer-masthead__brand {
  font-size: 20px;
  font-weight: 700;
  letter-spacing: 0.02em;
  color: var(--white);
}

.footer-masthead__brand:hover { color: var(--lime); }

.footer-masthead__sub {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--turf);
}

.footer-masthead__note {
  flex: 1 1 300px;
  font-size: 13px;
  line-height: 1.7;
  color: var(--grey);
  text-align: right;
}

.footer-cols {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 32px 28px;
  padding: 30px 0 34px;
  border-bottom: 1px solid var(--line);
}

.footer-col__title {
  margin-bottom: 14px;
  font-family: var(--font-mono);
  font-size: 10px;
  font-weight: 500;
  letter-spacing: 0.26em;
  color: var(--grey);
  text-transform: uppercase;
}

.footer-col__list {
  display: flex;
  flex-direction: column;
  gap: 9px;
}

.footer-col__list a {
  font-size: 14px;
  color: var(--white);
  border-bottom: 1px solid transparent;
  transition: color 0.16s var(--ease), border-color 0.16s var(--ease);
}

.footer-col__list a:hover {
  color: var(--lime);
  border-bottom-color: rgba(72, 224, 141, 0.45);
}

.footer-col__list a:focus-visible {
  outline: 2px solid var(--lime);
  outline-offset: 3px;
}

.footer-col__list--plain li {
  font-size: 13px;
  line-height: 1.7;
  color: var(--grey);
}

.footer-key {
  display: block;
  margin-bottom: 2px;
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.18em;
  color: var(--turf);
}

.footer-col__tip {
  margin-top: 12px;
  font-size: 12px;
  line-height: 1.7;
  color: var(--grey);
}

.footer-col__cta {
  display: inline-flex;
  margin-top: 14px;
  padding: 9px 16px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.1em;
  color: var(--white);
  border: 1px solid var(--yellow);
  background: rgba(245, 197, 24, 0.08);
  transition: background-color 0.18s var(--ease), color 0.18s var(--ease);
}

.footer-col__cta:hover {
  background: var(--yellow);
  color: #14100A;
}

.footer-base {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 8px 20px;
  padding-top: 20px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.04em;
  color: var(--grey);
}

.footer-base__icp { line-height: 1.6; }
.footer-base__copy { line-height: 1.6; }

/* ---------- 7. 通用布局 ---------- */
.shell {
  width: min(1180px, 100% - 56px);
  margin-inline: auto;
}

.grid-12 {
  display: grid;
  grid-template-columns: repeat(12, minmax(0, 1fr));
  gap: 20px;
}

.col-3 { grid-column: span 3; }
.col-5 { grid-column: span 5; }
.col-7 { grid-column: span 7; }
.col-9 { grid-column: span 9; }
.col-12 { grid-column: span 12; }

.section {
  padding: 64px 0;
  border-top: 1px solid var(--line);
}

.section--flush { border-top: 0; padding-top: 40px; }

.chapter-head {
  display: flex;
  align-items: baseline;
  gap: 14px;
  margin-bottom: 26px;
}

.chapter-head__num {
  flex: 0 0 auto;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.2em;
  color: var(--turf);
}

.chapter-head__title {
  font-size: clamp(26px, 3.4vw, 40px);
  font-weight: 600;
  line-height: 1.2;
  letter-spacing: -0.01em;
  color: var(--white);
}

.eyebrow {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.24em;
  color: var(--turf);
  text-transform: uppercase;
}

.display-xl {
  font-size: clamp(50px, 9vw, 120px);
  font-weight: 300;
  line-height: 0.98;
  letter-spacing: -0.02em;
}

.stat-figure {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(40px, 6vw, 72px);
  font-weight: 700;
  line-height: 1;
  letter-spacing: -0.02em;
  color: var(--white);
  font-variant-numeric: tabular-nums;
}

.stat-figure--yellow { color: var(--yellow); }
.stat-figure--red { color: var(--red-ink); }
.stat-figure--lime { color: var(--lime); }

.lead {
  max-width: 660px;
  font-size: clamp(17px, 1.8vw, 20px);
  line-height: 1.7;
  color: #CBDAEE;
}

/* ---------- 8. 正文 ---------- */
.prose {
  max-width: 720px;
  font-size: 17px;
  line-height: 1.85;
  color: #DCE6F5;
}

.prose > * + * { margin-top: 1.15em; }

.prose h2 {
  margin-top: 1.9em;
  font-size: 26px;
  line-height: 1.35;
  color: var(--white);
}

.prose h3 {
  margin-top: 1.6em;
  font-size: 19px;
  color: var(--white);
}

.prose a {
  color: var(--lime);
  border-bottom: 1px solid rgba(72, 224, 141, 0.4);
}

.prose a:hover { border-bottom-color: var(--lime); }

.prose ul,
.prose ol {
  display: flex;
  flex-direction: column;
  gap: 0.5em;
}

.prose ul li {
  position: relative;
  padding-left: 1.4em;
}

.prose ul li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.85em;
  width: 9px;
  height: 1px;
  background: var(--turf);
}

.prose ol { counter-reset: prose-counter; }

.prose ol li {
  position: relative;
  padding-left: 2.4em;
  counter-increment: prose-counter;
}

.prose ol li::before {
  content: counter(prose-counter, decimal-leading-zero);
  position: absolute;
  left: 0;
  top: 0.45em;
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--turf);
}

.prose blockquote {
  padding-left: 18px;
  border-left: 2px solid var(--turf);
  color: var(--grey);
}

.prose code {
  padding: 2px 6px;
  font-family: var(--font-mono);
  font-size: 0.9em;
  background: var(--panel);
  border: 1px solid var(--line);
}

/* ---------- 9. 面包屑 ---------- */
.crumbs {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--grey);
}

.crumbs a {
  color: var(--grey);
  border-bottom: 1px solid transparent;
}

.crumbs a:hover {
  color: var(--lime);
  border-bottom-color: rgba(72, 224, 141, 0.4);
}

.crumbs__sep { color: rgba(135, 148, 168, 0.5); }

.crumbs [aria-current="page"] { color: var(--white); }

/* ---------- 10. 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 20px;
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.04em;
  color: var(--white);
  background: transparent;
  border: 1px solid var(--line-strong);
  transition: background-color 0.18s var(--ease), border-color 0.18s var(--ease),
    color 0.18s var(--ease);
}

.btn:hover {
  border-color: var(--turf);
  background: rgba(31, 164, 91, 0.14);
}

.btn:focus-visible {
  outline: 2px solid var(--lime);
  outline-offset: 3px;
}

.btn--red {
  color: #FFFFFF;
  background: var(--red);
  border-color: var(--red);
}

.btn--red:hover {
  background: #C22F2F;
  border-color: #C22F2F;
}

.btn--solid {
  color: #04160C;
  background: var(--turf);
  border-color: var(--turf);
}

.btn--solid:hover {
  background: var(--lime);
  border-color: var(--lime);
}

.btn--quiet {
  color: var(--grey);
  border-color: var(--line);
}

.btn--quiet:hover {
  color: var(--white);
  border-color: var(--line-strong);
  background: rgba(255, 255, 255, 0.04);
}

/* ---------- 11. 卡片与数据 ---------- */
.card {
  position: relative;
  padding: 22px;
  background: var(--panel);
  border: 1px solid var(--line);
  transition: border-color 0.2s var(--ease);
}

.card:hover { border-color: var(--line-strong); }

.card__head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 14px;
}

.card__title {
  font-size: 17px;
  font-weight: 600;
  line-height: 1.4;
  color: var(--white);
}

.card__meta {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.1em;
  color: var(--grey);
  white-space: nowrap;
}

.badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 3px 8px;
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 700;
  line-height: 1.4;
  letter-spacing: 0.1em;
  border: 1px solid transparent;
}

.badge--red {
  color: var(--red-ink);
  background: rgba(226, 59, 59, 0.16);
  border-color: rgba(226, 59, 59, 0.44);
}

.badge--yellow {
  color: var(--yellow);
  background: rgba(245, 197, 24, 0.14);
  border-color: rgba(245, 197, 24, 0.42);
}

.badge--green {
  color: var(--lime);
  background: rgba(31, 164, 91, 0.16);
  border-color: rgba(31, 164, 91, 0.45);
}

.badge--grey {
  color: var(--grey);
  background: rgba(135, 148, 168, 0.12);
  border-color: var(--line-strong);
}

.tag-flag {
  font-style: italic;
  font-weight: 700;
  font-size: 15px;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.tag-flag--red { color: var(--red-ink); }
.tag-flag--yellow { color: var(--yellow); }

.data-table__wrap {
  overflow-x: auto;
  border: 1px solid var(--line);
}

.data-table__wrap .data-table {
  border: 0;
  min-width: 640px;
}

.data-table {
  font-size: 14px;
}

.data-table th,
.data-table td {
  padding: 11px 14px;
  text-align: left;
  border-bottom: 1px solid var(--line);
}

.data-table thead th {
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.14em;
  color: var(--grey);
  text-transform: uppercase;
  white-space: nowrap;
  background: rgba(255, 255, 255, 0.03);
  cursor: pointer;
  user-select: none;
}

.data-table thead th:hover { color: var(--white); }

.data-table tbody tr:hover { background: rgba(31, 164, 91, 0.06); }

.data-table td.is-num {
  font-family: var(--font-mono);
  font-weight: 600;
  color: var(--white);
  text-align: right;
  font-variant-numeric: tabular-nums;
}

/* ---------- 12. FAQ ---------- */
.faq-item { border-bottom: 1px solid var(--line); }

.faq-item__q {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 16px;
  width: 100%;
  padding: 18px 0;
  font-size: 16px;
  font-weight: 600;
  line-height: 1.6;
  text-align: left;
  color: var(--white);
}

.faq-item__q:hover { color: var(--lime); }

.faq-item__icon {
  flex: 0 0 auto;
  font-family: var(--font-mono);
  color: var(--turf);
}

.faq-item__a {
  max-width: 720px;
  padding: 0 0 20px;
  font-size: 15px;
  line-height: 1.8;
  color: var(--grey);
}

/* ---------- 13. 图片容器 ---------- */
.media-frame {
  position: relative;
  overflow: hidden;
  aspect-ratio: 16 / 9;
  background: linear-gradient(150deg, #16233A 0%, #0B1424 100%);
  border: 1px solid var(--line);
}

.media-frame img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  filter: contrast(1.14) saturate(1.06) brightness(0.86);
}

.media-frame::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background: radial-gradient(115% 95% at 50% 42%, rgba(5, 9, 18, 0) 40%, rgba(5, 9, 18, 0.74) 100%);
}

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

.media-frame__tag {
  position: absolute;
  left: 0;
  bottom: 0;
  z-index: 2;
  max-width: 82%;
  padding: 10px 16px;
  font-size: 12px;
  line-height: 1.6;
  color: var(--white);
  background: linear-gradient(90deg, rgba(10, 17, 32, 0.92), rgba(10, 17, 32, 0));
}

/* ---------- 14. 滚动显现 ---------- */
[data-reveal] {
  opacity: 0;
  transform: translateY(14px);
  transition: opacity 0.5s var(--ease), transform 0.5s var(--ease);
}

[data-reveal].is-visible {
  opacity: 1;
  transform: none;
}

/* ---------- 15. 平板与移动端 ---------- */
@media (max-width: 1023px) {
  body {
    padding-left: 0;
    padding-top: var(--topbar-h);
  }

  body::before { background-size: 38px 38px; }

  .progress-track { left: 0; }

  .track-header {
    top: 0;
    right: 0;
    bottom: auto;
    left: 0;
    width: auto;
    height: var(--topbar-h);
    flex-direction: row;
    align-items: center;
    gap: 12px;
    padding: 0 14px;
    border-right: 0;
    border-bottom: 1px solid var(--line);
    overflow: visible;
  }

  .track-header__brand {
    flex-direction: row;
    align-items: baseline;
    gap: 9px;
    margin-right: auto;
    padding: 0;
    border-bottom: 0;
    text-align: left;
    min-width: 0;
  }

  .brand {
    writing-mode: horizontal-tb;
    text-orientation: mixed;
    font-size: 15px;
    letter-spacing: 0.02em;
    white-space: nowrap;
  }

  .brand-sub {
    max-width: 42vw;
    font-size: 10px;
    line-height: 1.4;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
  }

  .nav-toggle {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 8px 11px;
    order: 3;
    font-family: var(--font-mono);
    font-size: 12px;
    letter-spacing: 0.14em;
    color: var(--white);
    border: 1px solid var(--line);
    background: rgba(255, 255, 255, 0.03);
  }

  .nav-toggle:hover { border-color: var(--line-strong); }

  .nav-toggle__icon {
    display: flex;
    flex-direction: column;
    justify-content: center;
    gap: 4px;
    width: 16px;
  }

  .nav-toggle__icon i {
    display: block;
    width: 100%;
    height: 1.5px;
    background: currentColor;
    transition: transform 0.2s var(--ease), opacity 0.2s var(--ease);
  }

  .nav-toggle[aria-expanded="true"] .nav-toggle__icon i:first-child {
    transform: translateY(2.75px) rotate(45deg);
  }

  .nav-toggle[aria-expanded="true"] .nav-toggle__icon i:last-child {
    transform: translateY(-2.75px) rotate(-45deg);
  }

  .nav-toggle__label { line-height: 1; }

  .site-nav {
    position: fixed;
    top: 0;
    left: 0;
    bottom: 0;
    z-index: 70;
    width: min(86vw, 320px);
    display: block;
    flex: 0 0 auto;
    padding: calc(var(--topbar-h) + 16px) 12px 24px;
    background: #0B1424;
    border-right: 1px solid var(--line-strong);
    overflow-y: auto;
    transform: translateX(-102%);
    transition: transform 0.26s var(--ease);
  }

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

  .site-nav__title {
    padding: 0 8px 10px;
    font-size: 10px;
    text-align: left;
  }

  .site-nav__list { gap: 2px; }

  .site-nav__item + .site-nav__item { border-top: 0; }

  .site-nav__link {
    flex-direction: row;
    align-items: baseline;
    gap: 10px;
    padding: 13px 10px;
    border-left-width: 3px;
  }

  .site-nav__idx { width: 22px; font-size: 10px; }

  .site-nav__label { font-size: 14px; }

  .round-rail {
    margin-top: 24px;
    padding: 16px 6px 0;
  }

  .round-rail__title { text-align: left; padding-left: 4px; }

  .round-rail__chips {
    flex-direction: row;
    flex-wrap: wrap;
    gap: 8px;
  }

  .chip {
    padding: 9px 14px;
    font-size: 12px;
  }

  html[data-nav-open]::after {
    content: "";
    position: fixed;
    inset: 0;
    z-index: 65;
    background: rgba(5, 9, 18, 0.64);
  }

  .col-3, .col-5, .col-7, .col-9 { grid-column: span 6; }

  .footer-cols { grid-template-columns: repeat(2, minmax(0, 1fr)); }

  .footer-masthead__note { text-align: left; }
}

@media (max-width: 640px) {
  .shell { width: calc(100% - 32px); }

  .site-footer__inner { width: calc(100% - 32px); }

  .section { padding: 48px 0; }

  .col-3, .col-5, .col-7, .col-9, .col-12 { grid-column: span 12; }

  .grid-12 { gap: 16px; }

  .footer-cols {
    grid-template-columns: 1fr;
    gap: 28px;
  }

  .footer-base { justify-content: flex-start; }

  .chapter-head { flex-direction: column; gap: 6px; }

  .display-xl { font-size: clamp(44px, 15vw, 72px); }
}

/* ---------- 16. 动效偏好 ---------- */
@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;
  }

  [data-reveal] {
    opacity: 1;
    transform: none;
    transition: none;
  }

  .site-nav { transition: none; }
}