/* ============================================================
   北大信研院东阳中心 — 全站样式
   设计基调：参考 aiit.org.cn（北大红 + 白底 + 中英双标题）
   ============================================================ */
:root {
  --pku-red: #94070A;
  --pku-red-dark: #6E0508;
  --pku-red-light: #FBF0F0;
  --ink: #2B2B2B;
  --ink-soft: #5A5A5A;
  --ink-mute: #8C8C8C;
  --line: #E6E2DC;
  --bg-soft: #F7F5F1;
  --bg-white: #FFFFFF;
  --font-sans: "PingFang SC", "Microsoft YaHei", "Noto Sans SC", "Helvetica Neue", Arial, sans-serif;
  --font-serif: "Noto Serif SC", "Songti SC", serif;
}

* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  font-family: var(--font-sans);
  color: var(--ink);
  background: var(--bg-white);
  font-size: 16px;
  line-height: 1.75;
}
a { color: inherit; text-decoration: none; }
ul { list-style: none; }
img { max-width: 100%; height: auto; display: block; }

.container { max-width: 1200px; margin: 0 auto; padding: 0 24px; }

/* ---------- 顶部通栏 ---------- */
.topbar {
  background: var(--pku-red-dark);
  color: rgba(255,255,255,.85);
  font-size: 13px;
}
.topbar .container {
  display: flex; justify-content: space-between; align-items: center;
  height: 34px;
}
.topbar a:hover { color: #fff; }

/* ---------- 导航 ---------- */
.header {
  position: sticky; top: 0; z-index: 100;
  background: rgba(255,255,255,.96);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--line);
}
.header .container {
  display: flex; align-items: center; justify-content: space-between;
  height: 76px;
}
.brand { display: flex; align-items: center; gap: 14px; flex-shrink: 0; }
.brand-logo { height: 44px; width: auto; display: block; }
.brand-divider { width: 1px; height: 30px; background: var(--line); }
.brand-sub {
  font-family: var(--font-serif);
  font-size: 21px; font-weight: 700; color: var(--pku-red);
  letter-spacing: 3px; white-space: nowrap;
}
.footer-logo { height: 34px; width: auto; margin-bottom: 14px; }
/* ---------- 导航（分组下拉） ---------- */
.nav { display: flex; gap: 2px; align-items: center; }
.nav-item { position: relative; }
.nav-item > a {
  display: flex; align-items: center; gap: 6px;
  padding: 10px 14px; font-size: 15px; color: var(--ink);
  border-radius: 6px; transition: all .2s; white-space: nowrap;
}
.nav-item > a:hover { color: var(--pku-red); background: var(--pku-red-light); }
.nav-item > a.active { color: var(--pku-red); font-weight: 600; }
.caret {
  width: 0; height: 0; flex: none;
  border-left: 4px solid transparent; border-right: 4px solid transparent;
  border-top: 4.5px solid currentColor; opacity: .5;
}

/* 下拉面板：外层负责悬浮桥，内层负责视觉盒 */
.submenu {
  position: absolute; top: 100%; left: 50%; transform: translateX(-50%);
  padding-top: 12px; display: none; z-index: 210;
}
.nav-item:hover > .submenu,
.nav-item:focus-within > .submenu { display: block; }
.submenu-box {
  background: #fff; border: 1px solid var(--line); border-radius: 8px;
  box-shadow: 0 18px 36px rgba(0,0,0,.12);
  padding: 10px; min-width: 216px;
}
.submenu-box a {
  display: block; padding: 8px 14px;
  font-size: 13.5px; color: var(--ink-soft);
  border-radius: 5px; white-space: nowrap; transition: all .15s;
}
.submenu-box a:hover { color: var(--pku-red); background: var(--pku-red-light); }
.sm-title {
  font-size: 11.5px; font-weight: 700; color: var(--ink-mute);
  letter-spacing: 2px; padding: 10px 14px 5px; white-space: nowrap;
}
.submenu-box .sm-title:not(:first-child) {
  border-top: 1px dashed var(--line); margin-top: 8px;
}

/* 赋能中心 mega 面板：双栏 */
.submenu-box.mega { display: flex; gap: 0; }
.mega-col { min-width: 218px; }
.mega-col + .mega-col {
  border-left: 1px dashed var(--line);
  margin-left: 8px; padding-left: 8px;
}

.nav-toggle { display: none; }

/* ---------- Hero ---------- */
.hero {
  position: relative;
  background: linear-gradient(135deg, #4A0407 0%, var(--pku-red) 55%, #B23A3E 100%);
  color: #fff;
  padding: 110px 0 130px;
  overflow: hidden;
}
.hero::after {
  content: "";
  position: absolute; right: -120px; top: -120px;
  width: 480px; height: 480px; border-radius: 50%;
  border: 70px solid rgba(255,255,255,.06);
}
.hero .container { position: relative; z-index: 1; }
.hero-kicker {
  display: inline-block;
  font-size: 14px; letter-spacing: 4px;
  border: 1px solid rgba(255,255,255,.4);
  padding: 4px 14px; border-radius: 999px;
  margin-bottom: 22px;
}
.hero h1 {
  font-family: var(--font-serif);
  font-size: 46px; font-weight: 700;
  letter-spacing: 2px; margin-bottom: 8px;
}
.hero h2 {
  font-size: 17px; font-weight: 400;
  color: rgba(255,255,255,.85);
  letter-spacing: 6px; margin-bottom: 26px;
}
.hero p.lead {
  max-width: 640px;
  font-size: 16px; color: rgba(255,255,255,.9);
  margin-bottom: 36px;
}
.hero-actions { display: flex; gap: 16px; flex-wrap: wrap; }
.btn {
  display: inline-block; padding: 12px 30px;
  border-radius: 4px; font-size: 15px;
  transition: all .2s;
}
.btn-primary { background: #fff; color: var(--pku-red); font-weight: 600; }
.btn-primary:hover { background: var(--pku-red-light); }
.btn-ghost { border: 1px solid rgba(255,255,255,.6); color: #fff; }
.btn-ghost:hover { background: rgba(255,255,255,.12); }

/* ---------- 子页 banner ---------- */
.page-banner {
  background: linear-gradient(120deg, #4A0407, var(--pku-red));
  color: #fff; padding: 64px 0;
}
.page-banner .crumb { font-size: 13px; color: rgba(255,255,255,.75); margin-top: 12px; }
.page-banner .crumb a:hover { color: #fff; }
.page-banner h1 { font-family: var(--font-serif); font-size: 34px; letter-spacing: 2px; }
.page-banner .sub {
  font-size: 13px; letter-spacing: 3px;
  text-transform: uppercase; color: rgba(255,255,255,.7);
}

/* ---------- 通用 section ---------- */
.section { padding: 80px 0; }
.section.alt { background: var(--bg-soft); }
.sec-head { text-align: center; margin-bottom: 48px; }
.sec-head h2 {
  font-family: var(--font-serif);
  font-size: 30px; font-weight: 700; color: var(--ink);
}
.sec-head h2 em { font-style: normal; color: var(--pku-red); }
.sec-head .en {
  font-size: 12px; letter-spacing: 4px; text-transform: uppercase;
  color: var(--ink-mute); margin-top: 6px;
}
.sec-head .bar {
  width: 44px; height: 3px; background: var(--pku-red);
  margin: 16px auto 0;
}
.sec-head.left { text-align: left; }
.sec-head.left .bar { margin-left: 0; }

/* ---------- 数据亮点 ---------- */
.stats { padding: 0; }
.stats-grid {
  display: grid; grid-template-columns: repeat(4, 1fr);
  background: #fff; border-radius: 10px;
  box-shadow: 0 10px 40px rgba(74,4,7,.10);
  transform: translateY(-56px);
}
.stat {
  padding: 38px 20px; text-align: center;
  border-left: 1px solid var(--line);
}
.stat:first-child { border-left: none; }
.stat .num {
  font-size: 40px; font-weight: 700; color: var(--pku-red);
  font-family: var(--font-serif); line-height: 1.2;
}
.stat .num span { font-size: 18px; }
.stat .label { font-size: 14px; color: var(--ink-soft); margin-top: 6px; }

/* ---------- 两大中心卡片 ---------- */
.duo-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 28px; }
.duo-card {
  background: #fff; border: 1px solid var(--line);
  border-radius: 10px; overflow: hidden;
  transition: all .25s;
  display: flex; flex-direction: column;
}
.duo-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 16px 40px rgba(74,4,7,.12);
  border-color: transparent;
}
.duo-card .cap {
  background: var(--pku-red); color: #fff;
  padding: 26px 30px;
}
.duo-card.teal .cap { background: #0F6E56; }
.duo-card .cap .en {
  font-size: 11px; letter-spacing: 2.5px; text-transform: uppercase;
  color: rgba(255,255,255,.7);
}
.duo-card .cap h3 { font-size: 22px; font-family: var(--font-serif); margin-top: 4px; }
.duo-card .body { padding: 28px 30px 30px; flex: 1; display: flex; flex-direction: column; }
.duo-card .body p { color: var(--ink-soft); font-size: 15px; flex: 1; }
.duo-card .body .tags { display: flex; flex-wrap: wrap; gap: 8px; margin: 20px 0; }
.tag {
  font-size: 12.5px; color: var(--pku-red);
  background: var(--pku-red-light);
  padding: 3px 12px; border-radius: 999px;
}
.duo-card.teal .tag { color: #0F6E56; background: #E1F5EE; }
.more-link { color: var(--pku-red); font-size: 14.5px; font-weight: 600; }
.more-link:hover { text-decoration: underline; }

/* ---------- 通用卡片网格 ---------- */
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
.grid-4 { display: grid; grid-template-columns: repeat(4, 1fr); gap: 24px; }
.grid-2 { display: grid; grid-template-columns: 1fr 1fr; gap: 24px; }
.card {
  background: #fff; border: 1px solid var(--line);
  border-radius: 10px; padding: 30px 28px;
  transition: all .25s;
}
.card:hover {
  box-shadow: 0 12px 32px rgba(0,0,0,.07);
  transform: translateY(-3px);
}
.card .icon {
  width: 52px; height: 52px; border-radius: 10px;
  background: var(--pku-red-light); color: var(--pku-red);
  display: flex; align-items: center; justify-content: center;
  font-size: 24px; margin-bottom: 18px;
  font-family: var(--font-serif); font-weight: 700;
}
.card h3 { font-size: 18px; margin-bottom: 10px; }
.card p { font-size: 14.5px; color: var(--ink-soft); }
.card.teal { border-top: 3px solid #0F6E56; }
.card.teal .icon { background: #E1F5EE; color: #0F6E56; }
.card.red { border-top: 3px solid var(--pku-red); }

/* ---------- 时间线 / 流程 ---------- */
.steps { display: grid; grid-template-columns: repeat(5, 1fr); gap: 18px; counter-reset: step; }
.step {
  background: #fff; border: 1px solid var(--line);
  border-radius: 10px; padding: 26px 20px; text-align: center;
  position: relative;
}
.step::before {
  counter-increment: step;
  content: "0" counter(step);
  display: inline-block;
  font-family: var(--font-serif); font-size: 26px; font-weight: 700;
  color: var(--pku-red); margin-bottom: 10px;
}
.step h4 { font-size: 16px; margin-bottom: 8px; }
.step p { font-size: 13px; color: var(--ink-soft); line-height: 1.6; }

.steps.cols-4 { grid-template-columns: repeat(4, 1fr); }

/* ---------- 图文清单 ---------- */
.pill-list li {
  position: relative;
  padding: 10px 0 10px 26px;
  border-bottom: 1px solid var(--line);
  font-size: 14.5px;
  color: var(--ink-soft);
}
.pill-list li::before {
  content: "";
  position: absolute; left: 4px; top: 19px;
  width: 8px; height: 8px; border-radius: 50%;
  background: var(--pku-red);
}
.pill-list.teal li::before { background: #0F6E56; }
.pill-list li:last-child { border-bottom: none; }
.pill-list li strong { color: var(--ink); }

/* ---------- 城市徽章（概念验证中心 · 城市行） ---------- */
.city-chips { display: flex; flex-wrap: wrap; gap: 12px; justify-content: center; margin-bottom: 36px; }
.city-chip {
  font-family: var(--font-serif); font-size: 16px; font-weight: 700;
  color: var(--pku-red); background: var(--pku-red-light);
  border: 1px solid #EBD5D6;
  padding: 8px 22px; border-radius: 999px;
  letter-spacing: 2px;
}
.city-chip.more { color: var(--ink-mute); background: var(--bg-soft); border-color: var(--line); }

/* ---------- 专题专栏 ---------- */
.coming {
  position: relative;
  background: #fff; border: 1px dashed #D8D2C8;
  border-radius: 10px; padding: 30px 28px;
  transition: all .25s;
}
.coming:hover { box-shadow: 0 12px 32px rgba(0,0,0,.06); transform: translateY(-3px); border-color: #C4BCAE; }
.coming .badge {
  position: absolute; top: 16px; right: 16px;
  font-size: 11.5px; color: var(--ink-mute);
  background: var(--bg-soft); border: 1px solid var(--line);
  padding: 2px 10px; border-radius: 999px;
}
.coming .icon {
  width: 52px; height: 52px; border-radius: 10px;
  background: var(--bg-soft); color: var(--ink-soft);
  display: flex; align-items: center; justify-content: center;
  font-size: 22px; margin-bottom: 18px;
  font-family: var(--font-serif); font-weight: 700;
}
.coming h3 { font-size: 18px; margin-bottom: 10px; }
.coming p { font-size: 14.5px; color: var(--ink-mute); }

.notice {
  max-width: 860px;
  background: var(--bg-soft); border-left: 3px solid var(--pku-red);
  padding: 14px 20px; border-radius: 0 6px 6px 0;
  font-size: 14px; color: var(--ink-soft);
}

/* 专题入口卡片（赋能中心/首页） */
.topic-card {
  display: flex; flex-direction: column;
  background: #fff; border: 1px solid var(--line);
  border-radius: 10px; padding: 26px 26px 22px;
  border-top: 4px solid var(--topic-color, var(--pku-red));
  transition: all .25s;
}
.topic-card:hover { transform: translateY(-4px); box-shadow: 0 14px 36px rgba(0,0,0,.09); }
.topic-card .dot-en {
  font-size: 11px; letter-spacing: 2.5px; text-transform: uppercase;
  color: var(--topic-color, var(--pku-red)); font-weight: 600;
}
.topic-card h3 { font-size: 19px; margin: 8px 0 10px; }
.topic-card p { font-size: 14px; color: var(--ink-soft); flex: 1; }
.topic-card .more-link { color: var(--topic-color, var(--pku-red)); }

/* ---------- 新闻列表 ---------- */
.news-item {
  display: flex; gap: 24px; padding: 26px 4px;
  border-bottom: 1px solid var(--line);
  align-items: flex-start;
}
.news-item .date {
  flex-shrink: 0; width: 74px; text-align: center;
  background: var(--bg-soft); border-radius: 8px;
  padding: 10px 6px;
}
.news-item .date .d { font-size: 24px; font-weight: 700; color: var(--pku-red); line-height: 1.2; font-family: var(--font-serif); }
.news-item .date .ym { font-size: 12px; color: var(--ink-mute); }
.news-item .info h4 { font-size: 16.5px; font-weight: 600; margin-bottom: 6px; transition: color .2s; }
.news-item .info h4:hover { color: var(--pku-red); }
.news-item .info p { font-size: 14px; color: var(--ink-soft); }
.news-item .meta { font-size: 12.5px; color: var(--ink-mute); margin-top: 6px; }
.news-label {
  display: inline-block; font-size: 12px;
  color: var(--pku-red); background: var(--pku-red-light);
  padding: 1px 10px; border-radius: 3px; margin-right: 10px;
  vertical-align: 2px;
}

/* ---------- 图文段落 ---------- */
.prose { max-width: 860px; }
.prose p { color: var(--ink-soft); font-size: 15.5px; margin-bottom: 16px; text-indent: 2em; }
.prose p strong { color: var(--ink); }

/* ---------- 联系 / 页脚 ---------- */
.footer { background: #26221F; color: rgba(255,255,255,.72); font-size: 14px; }
.footer-grid {
  display: grid; grid-template-columns: 1.4fr 1fr 1fr;
  gap: 40px; padding: 56px 0 40px;
}
.footer h4 { color: #fff; font-size: 16px; margin-bottom: 18px; }
.footer li { margin-bottom: 10px; }
.footer a:hover { color: #fff; }
.footer-brand .cn {
  font-family: var(--font-serif); color: #fff;
  font-size: 20px; margin-bottom: 12px;
}
.copyright {
  border-top: 1px solid rgba(255,255,255,.1);
  padding: 18px 0; font-size: 12.5px;
  color: rgba(255,255,255,.45);
  display: flex; justify-content: space-between; flex-wrap: wrap; gap: 8px;
}

/* ---------- 书院专题：重点书院详解 ---------- */
.aca { padding: 64px 0; }
.aca.alt { background: var(--bg-soft); }
.aca-head { display: flex; gap: 18px; align-items: flex-start; margin-bottom: 26px; }
.aca-no {
  font-family: var(--font-serif); font-size: 42px; font-weight: 700;
  color: #C9BFB2; line-height: 1;
}
.aca-head h3 { font-family: var(--font-serif); font-size: 24px; }
.aca-alias { font-style: normal; font-size: 14px; color: var(--ink-mute); margin-left: 10px; font-weight: 400; }
.aca-yao { font-size: 13.5px; color: var(--pku-red); margin-top: 6px; font-weight: 600; }
.aca-grid { display: grid; grid-template-columns: 380px 1fr; gap: 34px; align-items: start; }
.aca-media { display: flex; flex-direction: column; gap: 14px; }
.pic { position: relative; margin: 0; }
.pic img { border-radius: 10px; width: 100%; display: block; object-fit: cover; box-shadow: 0 3px 12px rgba(0,0,0,.07); }
.pic.main img { aspect-ratio: 16/9; }
.pic .tag {
  position: absolute; left: 10px; top: 10px;
  font-size: 11px; letter-spacing: 1px; color: #fff;
  padding: 3px 9px; border-radius: 3px; backdrop-filter: blur(2px);
}
.tag-real { background: rgba(35,110,72,.9); }   /* 实景 */
.tag-ai   { background: rgba(178,88,20,.9); }   /* 规划意向 */
.pic figcaption { font-size: 12.5px; color: var(--ink-mute); margin-top: 7px; line-height: 1.55; }
.aca-thumbs { display: grid; grid-template-columns: 1fr 1fr; gap: 14px 12px; margin-top: 2px; }
.aca-thumbs.cols-3 { grid-template-columns: 1fr 1fr 1fr; }
.aca-thumbs .pic img { aspect-ratio: 4/3; border-radius: 8px; }
.aca-thumbs .pic .tag { font-size: 10px; padding: 2px 7px; left: 8px; top: 8px; }
.aca-thumbs .pic figcaption { font-size: 11.5px; margin-top: 5px; }

/* ---------- 书院卡片网格 ---------- */
.aca-cards { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
.aca-card {
  display: block; background: #fff; border: 1px solid var(--line);
  border-radius: 12px; overflow: hidden; position: relative;
  transition: transform .25s ease, box-shadow .25s ease;
}
.aca-card:hover { transform: translateY(-4px); box-shadow: 0 14px 32px rgba(0,0,0,.10); }
.aca-card .pic img { aspect-ratio: 16/9; border-radius: 0; }
.aca-card .pic .tag { left: 12px; top: 12px; }
.aca-card-body { padding: 18px 20px 22px; position: relative; }
.aca-card-no {
  position: absolute; top: 14px; right: 18px;
  font-family: var(--font-serif); font-size: 30px; font-weight: 700;
  color: rgba(148,7,10,.14); line-height: 1;
}
.aca-card-body h3 {
  font-family: var(--font-serif); font-size: 20px; color: var(--ink);
  padding-right: 44px;
}
.aca-card-body h3 em {
  font-style: normal; font-size: 12.5px; color: var(--ink-mute);
  margin-left: 8px; font-weight: 400;
}
.aca-card-yao { font-size: 13px; color: var(--pku-red); font-weight: 600; margin: 8px 0 10px; }
.aca-card-body p { font-size: 13.5px; color: var(--ink-mute); line-height: 1.7; margin-bottom: 14px; }
.aca-card-more { font-size: 13px; color: var(--pku-red); font-weight: 600; letter-spacing: .5px; }
.aca-loc { font-size: 14px; color: var(--ink-soft); margin-bottom: 10px; }
.aca-loc strong { color: var(--ink); }
.aca-path {
  display: inline-block; font-size: 13px; color: var(--pku-red);
  background: var(--pku-red-light); border-radius: 999px;
  padding: 3px 14px; margin-bottom: 14px;
}
.aca-body .intro { font-size: 15px; color: var(--ink-soft); margin-bottom: 6px; }
.aca-body h4 {
  margin: 20px 0 6px; font-size: 16px; color: var(--pku-red);
  font-family: var(--font-serif);
}
.aca-body .pill-list li { padding: 8px 0 8px 24px; font-size: 14px; }

/* ---------- 响应式 ---------- */
/* 导航 5 组 + 品牌区在 1100px 以下放不下：折叠为汉堡菜单 */
@media (max-width: 1100px) {
  .nav {
    display: none; position: absolute; top: 76px; left: 0; right: 0;
    background: #fff; flex-direction: column; align-items: stretch;
    padding: 12px 24px 20px; gap: 0;
    border-bottom: 1px solid var(--line);
    box-shadow: 0 12px 24px rgba(0,0,0,.08);
    /* 菜单比屏幕高时必须能滚 —— 否则末尾项（AI+制造创新场景、联系我们）
       会被挤出屏幕且无法触达。
       ⚠️ 118px 是实测推导值，不是拍的：
          站点顶部结构 = topbar 34px + header 77px，而 .nav 的 top:76px 是相对
          header 定位的 → 菜单实际从 y≈110 开始；再留 8px 底部余量 → 118px。
          实测（390×844）若只减 88px，菜单盒会伸出视口 22px，
          末尾项「联系我们」被裁掉 1px。改页头结构后必须重新量这个值。
       dvh 处理移动端地址栏高度变化，vh 作回退。 */
    max-height: calc(100vh - 118px);
    max-height: calc(100dvh - 118px);
    overflow-y: auto;
    -webkit-overflow-scrolling: touch;
    overscroll-behavior: contain;

  }
  .nav.open { display: flex; }
  .nav-item > a { width: 100%; justify-content: space-between; }
  .submenu {
    display: block; position: static; transform: none; padding: 0;
  }
  .submenu-box { border: none; box-shadow: none; padding: 0 0 6px 18px; min-width: 0; }
  .submenu-box.mega { display: block; }
  .mega-col + .mega-col { border-left: none; margin-left: 0; padding-left: 0; }
  .nav-toggle {
    display: block; background: none; border: none; cursor: pointer;
    width: 40px; height: 40px; position: relative;
  }
  .nav-toggle span, .nav-toggle span::before, .nav-toggle span::after {
    content: ""; position: absolute; left: 8px; right: 8px;
    height: 2px; background: var(--ink); border-radius: 2px;
  }
  .nav-toggle span { top: 19px; }
  .nav-toggle span::before { top: -7px; }
  .nav-toggle span::after { top: 7px; }
}

@media (max-width: 960px) {
  .nav {
    display: none; position: absolute; top: 76px; left: 0; right: 0;
    background: #fff; flex-direction: column; padding: 12px 24px 20px;
    border-bottom: 1px solid var(--line);
    box-shadow: 0 12px 24px rgba(0,0,0,.08);
    /* 菜单比屏幕高时必须能滚 —— 否则末尾项（AI+制造创新场景、联系我们）
       会被挤出屏幕且无法触达。
       ⚠️ 118px 是实测推导值，不是拍的：
          站点顶部结构 = topbar 34px + header 77px，而 .nav 的 top:76px 是相对
          header 定位的 → 菜单实际从 y≈110 开始；再留 8px 底部余量 → 118px。
          实测（390×844）若只减 88px，菜单盒会伸出视口 22px，
          末尾项「联系我们」被裁掉 1px。改页头结构后必须重新量这个值。
       dvh 处理移动端地址栏高度变化，vh 作回退。 */
    max-height: calc(100vh - 118px);
    max-height: calc(100dvh - 118px);
    overflow-y: auto;
    -webkit-overflow-scrolling: touch;
    overscroll-behavior: contain;

  }
  .nav.open { display: flex; }
  .nav-toggle {
    display: block; background: none; border: none; cursor: pointer;
    width: 40px; height: 40px; position: relative;
  }
  .nav-toggle span, .nav-toggle span::before, .nav-toggle span::after {
    content: ""; position: absolute; left: 8px; right: 8px;
    height: 2px; background: var(--ink); border-radius: 2px;
  }
  .nav-toggle span { top: 19px; }
  .nav-toggle span::before { top: -7px; }
  .nav-toggle span::after { top: 7px; }
  .hero h1 { font-size: 32px; }
  .stats-grid { grid-template-columns: repeat(2, 1fr); transform: translateY(-30px); }
  .stat { border-top: 1px solid var(--line); }
  .duo-grid, .grid-3, .grid-4, .grid-2 { grid-template-columns: 1fr; }
  .aca-cards { grid-template-columns: 1fr; }
  .aca-thumbs, .aca-thumbs.cols-3 { grid-template-columns: 1fr 1fr; }
  .aca-grid { grid-template-columns: 1fr; }
  .aca-head { gap: 12px; }
  .aca-no { font-size: 32px; }
  .steps, .steps.cols-4 { grid-template-columns: repeat(2, 1fr); }
  .footer-grid { grid-template-columns: 1fr; gap: 28px; }
  /* 页眉品牌区：窄屏缩放，修正横向溢出 */
  .brand { gap: 9px; min-width: 0; }
  .brand-logo { height: 30px; }
  .brand-divider { height: 22px; }
  .brand-sub { font-size: 15px; letter-spacing: .5px; }
}

/* 超窄屏（小手机）：步骤卡改单列，避免内容撑破卡片 */
@media (max-width: 560px) {
  .steps, .steps.cols-4 { grid-template-columns: 1fr; }
  .brand-logo { height: 26px; }
  .brand-sub { font-size: 14px; letter-spacing: 0; }
}

/* ---------- 书院专题：双 Tab ---------- */
.shuyuan-tabs {
  background: #fff; border-bottom: 1px solid var(--line);
  position: sticky; top: 76px; z-index: 60;
}
.shuyuan-tabs .container { display: flex; gap: 8px; justify-content: center; }
.sy-tab {
  display: inline-block; padding: 16px 34px 14px; font-size: 16.5px; font-weight: 600;
  color: var(--ink-mute); border: none; background: none; cursor: pointer;
  border-bottom: 3px solid transparent; font-family: inherit; transition: all .2s;
}
.sy-tab:hover { color: var(--pku-red); }
.sy-tab.active { color: var(--pku-red); border-bottom-color: var(--pku-red); }
.sy-tab .en { display: block; font-size: 11px; font-weight: 400; color: var(--ink-mute); letter-spacing: .5px; margin-top: 2px; text-transform: uppercase; }
.tab-pane[hidden] { display: none; }

/* ---------- 时间线 ---------- */
.timeline { max-width: 880px; margin: 0 auto; position: relative; padding-left: 34px; }
.timeline::before {
  content: ""; position: absolute; left: 9px; top: 8px; bottom: 8px;
  width: 2px; background: linear-gradient(var(--pku-red), #C9A227);
}
.tl-item { position: relative; padding: 0 0 34px 18px; }
.tl-item:last-child { padding-bottom: 0; }
.tl-item::before {
  content: ""; position: absolute; left: -32px; top: 6px; width: 14px; height: 14px;
  border-radius: 50%; background: #fff; border: 3px solid var(--pku-red);
}
.tl-era { font-size: 21px; font-weight: 700; color: var(--ink); font-family: var(--font-serif, serif); }
.tl-era .cnt {
  font-size: 12.5px; font-weight: 600; color: var(--pku-red); background: rgba(148,7,10,.07);
  border: 1px solid rgba(148,7,10,.2); border-radius: 20px; padding: 2px 12px; margin-left: 10px; vertical-align: 3px;
}
.tl-item p { margin: 8px 0 0; color: #444; font-size: 14.5px; line-height: 1.8; }
.tl-item p strong { color: var(--ink); }

/* ---------- 人物线 ---------- */
.person-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; }
.person-card {
  background: #fff; border: 1px solid var(--line); border-radius: 12px;
  padding: 22px 22px 18px; border-top: 3px solid var(--pku-red);
  display: flex; flex-direction: column; transition: all .25s;
}
.person-card:hover { box-shadow: 0 10px 28px rgba(0,0,0,.09); transform: translateY(-3px); }
.person-card h4 { font-size: 17px; margin: 0 0 2px; }
.person-card h4 em { font-style: normal; font-size: 12px; color: var(--ink-mute); font-weight: 400; margin-left: 8px; }
.person-card .role { font-size: 12.5px; color: #8a6d1d; font-weight: 600; margin-bottom: 8px; }
.person-card p { font-size: 13.5px; color: #555; line-height: 1.75; margin: 0 0 12px; flex: 1; }
.src-links { list-style: none; margin: 0; padding: 0; }
.src-links li { margin: 0 0 6px; }
.src-links a {
  display: inline-flex; align-items: center; gap: 6px; font-size: 13px; font-weight: 600;
  color: var(--pku-red); text-decoration: none; border-bottom: 1px dashed rgba(148,7,10,.35); padding-bottom: 1px;
}
.src-links a::before { content: "❧"; font-size: 12px; }
.src-links a:hover { border-bottom-style: solid; }

/* ---------- 书院线：原著记载列表 ---------- */
.reader-list { max-width: 880px; margin: 0 auto; }
.reader-list li {
  list-style: none; background: #fff; border: 1px solid var(--line); border-radius: 10px;
  padding: 14px 18px; margin-bottom: 10px; display: flex; align-items: baseline; gap: 14px; flex-wrap: wrap;
}
.reader-list li a { font-weight: 600; color: var(--ink); font-size: 15px; text-decoration: none; }
.reader-list li a:hover { color: var(--pku-red); }
.reader-list .src { font-size: 12.5px; color: var(--ink-mute); }
.reader-list .to { margin-left: auto; font-size: 13px; color: var(--pku-red); font-weight: 600; }

/* ---------- 原著摘录页排版 ---------- */
.book-meta {
  display: flex; gap: 12px; flex-wrap: wrap; align-items: center;
  margin: 34px auto 0; max-width: 820px;
}
.book-part {
  background: var(--pku-red); color: #fff; font-size: 13px; font-weight: 600;
  border-radius: 4px; padding: 3px 12px;
}
.book-src, .book-pg { font-size: 13px; color: var(--ink-mute); }
.book-lead {
  max-width: 820px; margin: 16px auto 30px; font-size: 15px; color: #6b4a2b;
  background: #faf6ef; border-left: 3px solid #C9A227; padding: 12px 18px; line-height: 1.8; border-radius: 0 8px 8px 0;
}
.book-body {
  max-width: 820px; margin: 0 auto; background: #fff; border: 1px solid var(--line);
  border-radius: 12px; padding: 36px 40px;
}
.book-body p {
  font-family: "Songti SC", "Noto Serif SC", serif; font-size: 15.5px; line-height: 2.0;
  color: #2d2d2d; text-align: justify; margin: 0 0 18px; text-indent: 2em;
}
.book-body p:first-child { text-indent: 0; }
.book-note {
  max-width: 820px; margin: 22px auto 0; font-size: 12.5px; color: var(--ink-mute); line-height: 1.8;
}
.reader-cta { text-align: center; margin: 26px 0 40px; }
.reader-groups { max-width: 880px; margin: 0 auto; display: grid; grid-template-columns: 1fr 1fr; gap: 18px; }
.reader-group { background: #fff; border: 1px solid var(--line); border-radius: 12px; padding: 20px 22px; }
.reader-group h4 { margin: 0 0 12px; font-size: 16px; display: flex; align-items: center; justify-content: space-between; }
.reader-group h4 .g-link { font-size: 12.5px; font-weight: 600; color: var(--pku-red); text-decoration: none; }
.reader-group ul { margin: 0; padding: 0; }
.reader-group li { list-style: none; padding: 7px 0; border-bottom: 1px dashed var(--line); display: flex; align-items: baseline; gap: 10px; flex-wrap: wrap; }
.reader-group li:last-child { border-bottom: none; }
.reader-group li a { font-weight: 600; font-size: 14px; color: var(--ink); text-decoration: none; }
.reader-group li a:hover { color: var(--pku-red); }
.reader-group .src { font-size: 12px; color: var(--ink-mute); margin-left: auto; }

@media (max-width: 960px) {
  .person-grid, .reader-groups { grid-template-columns: 1fr; }
  .book-body { padding: 24px 20px; }
  .shuyuan-tabs .container { justify-content: flex-start; overflow-x: auto; }
  .sy-tab { padding: 13px 20px 11px; font-size: 15px; white-space: nowrap; }
  .shuyuan-tabs { top: 64px; }
}

/* ---------- 浅色内容区上的按钮 ----------
   .btn-primary（白底红字）与 .btn-ghost（白字半透明边框）都是为深色 banner 设计的；
   直接用在 .section（白 / 浅灰）里，.btn-ghost 会变成「白字白底」完全看不见。
   这里按上下文覆盖，不改动原类，深色区（page-banner 等）不受影响。 */
.section .btn-primary { background: var(--pku-red); color: #fff; font-weight: 600; }
.section .btn-primary:hover { background: #7a0509; color: #fff; }
.section .btn-ghost { border: 1px solid var(--line); color: var(--ink); }
.section .btn-ghost:hover { background: #fff; border-color: var(--pku-red); color: var(--pku-red); }

/* ---------- 可点击的数据卡（点开看明细） ----------
   把 div.stat 换成 a.stat（链接）后，仍保持原观感，并自动追加「查看明细 →」提示。
   素材与站点既有 .stat 样式共用，不覆盖其任何属性。 */
a.stat { display: block; text-decoration: none; color: inherit; transition: background .2s ease; }
a.stat:hover { background: var(--pku-red-light); }
a.stat::after {
  content: '查看明细 →';
  display: block; margin-top: 7px;
  font-size: 11.5px; font-weight: 600; letter-spacing: .3px;
  color: var(--pku-red);
}
a.stat:focus-visible { outline: 2px solid var(--pku-red); outline-offset: -2px; }

/* ---------- 锚点定位 ----------
   页内跳转（数据卡下钻）落点要避开吸顶的 header，留出约 88px。 */
[id] { scroll-margin-top: 88px; }