/* MrTimsMathCafe / Element万物皆数 - 全站样式
   设计：温暖米白底 + 深海军蓝文字 + 数学符号装饰，明亮主题 */

:root {
  --bg: #f7f3ea;
  --bg-alt: #fefcf6;
  --bg-card: #ffffff;
  --text: #1a2540;
  --text-soft: #4a5573;
  --text-mute: #8a92a8;
  --line: #e3dccb;
  --accent: #c8553d;       /* terracotta */
  --accent-soft: #f4d5cc;
  --gold: #d4a017;
  --sage: #6b8e5a;
  --sage-soft: #d7e1cc;
  --indigo: #2d3a6b;
  --indigo-soft: #d5d9e8;
  --shadow: 0 4px 14px rgba(26, 37, 64, 0.06);
  --shadow-hover: 0 10px 28px rgba(26, 37, 64, 0.12);
  --radius: 14px;
  --radius-sm: 8px;
  --maxw: 1180px;
  --serif: 'Georgia', 'Times New Roman', 'Noto Serif SC', serif;
  --sans: -apple-system, BlinkMacSystemFont, 'Helvetica Neue', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --mono: 'SF Mono', Menlo, Consolas, monospace;
}

* { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
body {
  font-family: var(--sans);
  background: var(--bg);
  color: var(--text);
  line-height: 1.65;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
}
a { color: var(--accent); text-decoration: none; transition: color .15s; }
a:hover { color: var(--indigo); }

/* ========== 顶部导航 ========== */
.site-header {
  position: sticky; top: 0; z-index: 50;
  background: rgba(247, 243, 234, 0.92);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--line);
}
.nav {
  max-width: var(--maxw); margin: 0 auto;
  padding: 14px 24px;
  display: flex; align-items: center; gap: 28px;
}
.brand {
  display: flex; align-items: center; gap: 10px;
  font-family: var(--serif);
  font-size: 1.18rem; font-weight: 700; color: var(--indigo);
  letter-spacing: 0.3px;
}
.brand .glyph {
  font-size: 1.4rem; color: var(--accent);
}
.brand small { display: block; font-size: 0.68rem; font-family: var(--sans);
  color: var(--text-mute); font-weight: 400; letter-spacing: 0.5px; }
.nav-links { display: flex; gap: 22px; flex: 1; flex-wrap: wrap; }
.nav-links a { color: var(--text-soft); font-size: 0.93rem; font-weight: 500; }
.nav-links a:hover { color: var(--accent); }
.nav-search {
  display: flex; align-items: center; gap: 8px;
  background: var(--bg-card); border: 1px solid var(--line);
  padding: 6px 12px; border-radius: 999px;
  min-width: 200px;
}
.nav-search input {
  border: none; background: transparent; outline: none;
  font-size: 0.9rem; flex: 1; color: var(--text); font-family: var(--sans);
}
.nav-search .ico { color: var(--text-mute); font-size: 0.95rem; }
.menu-toggle {
  display: none; background: none; border: 1px solid var(--line);
  border-radius: 8px; padding: 6px 10px; cursor: pointer; color: var(--text);
}

/* ========== Hero ========== */
.hero {
  position: relative; overflow: hidden;
  background: linear-gradient(135deg, #fefcf6 0%, #f0e7d4 100%);
  border-bottom: 1px solid var(--line);
}
.hero-inner {
  max-width: var(--maxw); margin: 0 auto;
  padding: 64px 24px 56px;
  position: relative; z-index: 2;
}
.hero .watermark {
  position: absolute; font-family: var(--serif);
  color: rgba(200, 85, 61, 0.06); font-size: 18rem; font-weight: 700;
  top: -40px; right: 20px; line-height: 1; user-select: none;
}
.hero h1 {
  font-family: var(--serif); font-size: clamp(2.2rem, 5.5vw, 3.8rem);
  margin-bottom: 16px; letter-spacing: 0.5px;
  background: linear-gradient(115deg, var(--indigo) 30%, var(--accent) 85%);
  -webkit-background-clip: text; background-clip: text;
  -webkit-text-fill-color: transparent; color: var(--indigo);
}
.hero h1::after {
  content: ""; display: block; width: 72px; height: 5px;
  margin-top: 14px; border-radius: 3px;
  background: linear-gradient(90deg, var(--accent), rgba(200, 85, 61, 0.25));
}
.hero .tagline {
  font-size: 1.15rem; color: var(--text-soft);
  max-width: 640px; margin-bottom: 26px;
}
.hero .tagline em { color: var(--accent); font-style: normal; font-weight: 600; }
.hero .cta-row { display: flex; gap: 14px; flex-wrap: wrap; }
.btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 11px 22px; border-radius: 999px;
  font-weight: 600; font-size: 0.95rem;
  border: 1px solid transparent; cursor: pointer;
  transition: all .2s;
}
.btn-primary { background: var(--accent); color: #fff; }
.btn-primary:hover { background: var(--indigo); color: #fff; }
.btn-ghost { background: transparent; border-color: var(--line); color: var(--text); }
.btn-ghost:hover { border-color: var(--accent); color: var(--accent); }

/* ========== 板块卡片网格 ========== */
.section { max-width: var(--maxw); margin: 0 auto; padding: 56px 24px; }
.section-head {
  display: flex; align-items: baseline; justify-content: space-between;
  margin-bottom: 28px; flex-wrap: wrap; gap: 12px;
}
.section-head h2 {
  font-family: var(--serif); font-size: 1.7rem; color: var(--indigo);
  letter-spacing: -0.3px;
}
.section-head h2 .glyph { color: var(--accent); margin-right: 8px; }
.section-head .sub { color: var(--text-mute); font-size: 0.95rem; }

.grid {
  display: grid; gap: 20px;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
}
.card {
  background: var(--bg-card); border-radius: var(--radius);
  border: 1px solid var(--line); padding: 24px;
  box-shadow: var(--shadow); transition: all .2s;
  position: relative; overflow: hidden;
}
.card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-hover);
  border-color: var(--accent-soft);
}
.card .glyph {
  font-family: var(--serif); font-size: 2rem;
  color: var(--accent); margin-bottom: 10px; display: block;
}
.card h3 { font-family: var(--serif); font-size: 1.25rem; color: var(--indigo);
  margin-bottom: 8px; }
.card p { color: var(--text-soft); font-size: 0.92rem; margin-bottom: 14px; }
.card .tags { display: flex; flex-wrap: wrap; gap: 6px; margin-bottom: 14px; }
.tag {
  font-size: 0.74rem; padding: 3px 10px;
  background: var(--bg-alt); border: 1px solid var(--line);
  border-radius: 999px; color: var(--text-soft);
}
.card .more {
  display: inline-flex; align-items: center; gap: 6px;
  font-size: 0.88rem; font-weight: 600; color: var(--accent);
}

/* 不同板块用不同色 */
.card.caie   { border-top: 3px solid var(--accent); }
.card.edx    { border-top: 3px solid var(--indigo); }
.card.mid    { border-top: 3px solid var(--sage); }
.card.pri    { border-top: 3px solid var(--gold); }
.card.app    { border-top: 3px solid #8b5a9f; }
.card.ict    { border-top: 3px solid #4a7c8c; }
.card.step   { border-top: 3px solid #2a6f97; }
.card.ap     { border-top: 3px solid #6a4c93; }
.card.ib     { border-top: 3px solid #1b998b; }
.card.fun    { border-top: 3px solid #d97742; }
.card.enl    { border-top: 3px solid #6c8c5a; }
.card.uni    { border-top: 3px solid #5b4b8a; }   /* 大学数学：深紫 */
.card.comp   { border-top: 3px solid #b85450; }   /* 竞赛数学：砖红 */

/* ========== 子板块列表 ========== */
.subsection-grid {
  display: grid; gap: 16px;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  margin-top: 8px;
}
.sub-card {
  background: var(--bg-card); border: 1px solid var(--line);
  border-radius: var(--radius-sm); padding: 20px;
  transition: all .2s;
}
.sub-card:hover {
  border-color: var(--accent); transform: translateY(-2px);
  box-shadow: var(--shadow);
}
.sub-card .code {
  font-family: var(--mono); font-size: 0.78rem;
  color: var(--accent); font-weight: 600; letter-spacing: 0.5px;
}
.sub-card h4 { font-family: var(--serif); color: var(--indigo);
  margin: 6px 0 8px; font-size: 1.05rem; }
.sub-card .count {
  font-size: 0.82rem; color: var(--text-mute);
}

/* ========== 内容列表（视频/文章） ========== */
.content-list { display: flex; flex-direction: column; gap: 14px; }
.content-row {
  display: flex; flex-wrap: wrap; gap: 18px; align-items: flex-start;
  background: var(--bg-card); border: 1px solid var(--line);
  border-radius: var(--radius-sm); padding: 16px 20px;
  transition: all .2s;
}
.content-row:hover { border-color: var(--accent); box-shadow: var(--shadow); }
.content-row .badge {
  flex-shrink: 0; width: 56px; height: 56px;
  border-radius: 10px; display: flex; align-items: center; justify-content: center;
  font-family: var(--serif); font-size: 1.4rem; color: #fff;
}
.badge.video { background: linear-gradient(135deg, #c8553d, #d97742); }
.badge.article { background: linear-gradient(135deg, #2d3a6b, #4a5a8c); }
.content-row .body { flex: 1; min-width: 0; }
.content-row h4 {
  font-size: 1.05rem; color: var(--indigo); margin-bottom: 4px;
  font-family: var(--serif);
}
.content-row h4 a { color: inherit; }
.content-row h4 a:hover { color: var(--accent); }
.content-row .meta {
  font-size: 0.82rem; color: var(--text-mute);
  display: flex; gap: 14px; flex-wrap: wrap;
}
.content-row .meta span::before {
  content: '·'; margin-right: 8px; color: var(--line);
}
.content-row .meta span:first-child::before { content: ''; margin: 0; }

/* 视频嵌入：在线观看按钮 + iframe 容器 */
.content-row .actions {
  margin-top: 10px;
  display: flex; gap: 14px; align-items: center; flex-wrap: wrap;
}
.embed-btn {
  background: var(--accent); color: #fff; border: none;
  padding: 7px 16px; border-radius: 999px;
  font-size: 0.85rem; font-weight: 600; cursor: pointer;
  transition: all .15s; font-family: var(--sans);
}
.embed-btn:hover { background: var(--indigo); }
.embed-btn.active { background: var(--text-mute); }
.embed-wrapper {
  flex-basis: 100%; margin-top: 12px; display: none;
}
.embed-wrapper.active { display: block; }
.embed-wrapper iframe {
  width: 100%; aspect-ratio: 16/9; border: 0;
  border-radius: var(--radius-sm); background: #000;
}
.ext-link {
  font-size: 0.85rem; color: var(--text-soft);
  display: inline-flex; align-items: center; gap: 4px;
}
.ext-link:hover { color: var(--accent); }
.content-row .meta span:first-child::before { content: ''; margin: 0; }

/* ========== 关于页 ========== */
.about-wrap { max-width: 760px; margin: 0 auto; padding: 64px 24px; }
.about-wrap h1 {
  font-family: var(--serif); font-size: 2.2rem; color: var(--indigo);
  margin-bottom: 8px;
}
.about-wrap .lead { color: var(--text-soft); font-size: 1.1rem;
  margin-bottom: 32px; padding-bottom: 24px; border-bottom: 1px solid var(--line); }
.about-wrap h2 {
  font-family: var(--serif); color: var(--indigo);
  font-size: 1.4rem; margin: 28px 0 12px;
}
.about-wrap p { margin-bottom: 14px; color: var(--text-soft); }
.about-wrap .channels { display: flex; gap: 14px; flex-wrap: wrap; margin-top: 20px; }
.channel {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 10px 16px; border: 1px solid var(--line);
  border-radius: 999px; background: var(--bg-card);
  font-size: 0.9rem; color: var(--text-soft);
}
.channel:hover { border-color: var(--accent); color: var(--accent); }

/* ========== 搜索页 ========== */
.search-wrap { max-width: 880px; margin: 0 auto; padding: 48px 24px; }
.search-box {
  display: flex; align-items: center; gap: 12px;
  background: var(--bg-card); border: 2px solid var(--line);
  border-radius: 999px; padding: 14px 22px;
  margin-bottom: 24px; transition: border-color .2s;
}
.search-box:focus-within { border-color: var(--accent); }
.search-box input {
  flex: 1; border: none; outline: none; background: transparent;
  font-size: 1.05rem; color: var(--text); font-family: var(--sans);
}
.filter-row { display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 24px; }
.filter-btn {
  padding: 6px 14px; border-radius: 999px;
  border: 1px solid var(--line); background: var(--bg-card);
  font-size: 0.85rem; color: var(--text-soft); cursor: pointer;
  transition: all .15s;
}
.filter-btn.active, .filter-btn:hover {
  background: var(--indigo); color: #fff; border-color: var(--indigo);
}
.search-stats { color: var(--text-mute); font-size: 0.88rem; margin-bottom: 16px; }
.empty {
  text-align: center; padding: 60px 20px; color: var(--text-mute);
}
.empty .glyph { font-family: var(--serif); font-size: 3rem;
  color: var(--line); display: block; margin-bottom: 12px; }

/* 高亮搜索结果 */
mark { background: var(--accent-soft); color: var(--accent);
  padding: 0 3px; border-radius: 3px; }

/* ========== 子页头部 ========== */
.page-hero {
  background: linear-gradient(135deg, var(--bg-alt) 0%, var(--bg) 100%);
  border-bottom: 1px solid var(--line);
}
.page-hero-inner {
  max-width: var(--maxw); margin: 0 auto; padding: 40px 24px 28px;
}
.breadcrumb {
  font-size: 0.84rem; color: var(--text-mute);
  margin-bottom: 12px;
}
.breadcrumb a { color: var(--text-soft); }
.breadcrumb .sep { margin: 0 8px; }
.page-hero h1 {
  font-family: var(--serif); color: var(--indigo);
  font-size: 2rem; margin-bottom: 8px;
}
.page-hero .desc { color: var(--text-soft); max-width: 640px; }

/* ========== 页脚 ========== */
.site-footer {
  background: var(--indigo); color: rgba(255,255,255,0.85);
  padding: 40px 24px 24px; margin-top: 60px;
}
.footer-inner {
  max-width: var(--maxw); margin: 0 auto;
  display: flex; flex-wrap: wrap; gap: 32px; justify-content: space-between;
}
.footer-inner h5 { font-family: var(--serif); font-size: 1rem;
  color: #fff; margin-bottom: 10px; }
.footer-inner a { color: rgba(255,255,255,0.75); font-size: 0.88rem; display: block;
  padding: 3px 0; }
.footer-inner a:hover { color: #fff; }
.footer-bottom {
  max-width: var(--maxw); margin: 32px auto 0; padding-top: 20px;
  border-top: 1px solid rgba(255,255,255,0.15);
  text-align: center; font-size: 0.82rem;
  color: rgba(255,255,255,0.55);
}

/* ========== 响应式：三档断点 手机/iPad/电脑 ========== */

/* iPad 竖屏（769-1024px）：导航两行、卡片网格调整 */
@media (max-width: 1024px) {
  .nav { flex-wrap: wrap; gap: 12px; padding: 12px 20px; }
  .nav-links { gap: 14px; font-size: 0.88rem; }
  .nav-search { min-width: 160px; }
  .hero .watermark { font-size: 14rem; }
  .grid { grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); gap: 16px; }
  .subsection-grid { grid-template-columns: repeat(auto-fill, minmax(180px, 1fr)); }
  .footer-inner { gap: 24px; }
}

/* 手机 + iPad 横屏（≤768px）：汉堡菜单、单列内容 */
@media (max-width: 768px) {
  .nav { flex-wrap: wrap; gap: 14px; }
  .nav-search { display: none; }
  .menu-toggle { display: block; }
  .nav-links { display: none; flex-basis: 100%; flex-direction: column; gap: 10px; padding-top: 10px; }
  .nav-links.open { display: flex; }
  .hero-inner { padding: 44px 20px; }
  .hero h1 { font-size: 2rem; }
  .hero .watermark { font-size: 10rem; top: -20px; }
  .section { padding: 40px 20px; }
  .grid { grid-template-columns: 1fr; }
  .subsection-grid { grid-template-columns: repeat(auto-fill, minmax(160px, 1fr)); }
  .content-row { flex-direction: column; gap: 12px; }
  .content-row .badge { width: 44px; height: 44px; font-size: 1.1rem; }
  .content-row .actions { gap: 10px; }
  .embed-btn { padding: 6px 12px; font-size: 0.82rem; }
  .footer-inner { flex-direction: column; gap: 20px; }
  .search-box { padding: 12px 18px; }
  .search-box input { font-size: 0.95rem; }
}

/* 小手机（≤480px）：进一步紧凑 */
@media (max-width: 480px) {
  .hero-inner { padding: 32px 16px; }
  .hero h1 { font-size: 1.7rem; }
  .hero .tagline { font-size: 0.95rem; }
  .cta-row { flex-direction: column; }
  .cta-row .btn { width: 100%; justify-content: center; }
  .section { padding: 32px 16px; }
  .section-head h2 { font-size: 1.3rem; }
  .card { padding: 18px; }
  .content-row { padding: 14px 16px; }
  .embed-wrapper iframe { aspect-ratio: 4/3; }
  .tabs { flex-wrap: wrap; }
  .tab-btn { font-size: 0.82rem; padding: 10px 12px; }
  .countdown-display span { font-size: 1.8rem; }
  .cover-grid { grid-template-columns: 1fr 1fr; }
}

/* ========== Tab 切换系统 ========== */
.tabs {
  display: flex; gap: 2px;
  border-bottom: 2px solid var(--line);
  margin-bottom: 28px; overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}
.tab-btn {
  padding: 12px 18px; border: none; background: transparent;
  font-family: var(--sans); font-size: 0.92rem; color: var(--text-soft);
  cursor: pointer; border-bottom: 2px solid transparent; margin-bottom: -2px;
  transition: all .15s; white-space: nowrap;
}
.tab-btn:hover { color: var(--accent); }
.tab-btn.active {
  color: var(--accent); border-bottom-color: var(--accent); font-weight: 600;
}
.tab-content { display: none; }
.tab-content.active { display: block; animation: fadeIn .2s; }
@keyframes fadeIn { from { opacity: 0; } to { opacity: 1; } }
.tab-placeholder {
  text-align: center; padding: 60px 20px; color: var(--text-mute);
}
.tab-placeholder .glyph {
  font-size: 2.5rem; display: block; margin-bottom: 10px; color: var(--line);
}

/* ========== 封面图卡片 ========== */
.cover-grid {
  display: grid; gap: 20px;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
}
.cover-card {
  background: var(--bg-card); border: 1px solid var(--line);
  border-radius: var(--radius); overflow: hidden;
  transition: all .2s; display: block; text-decoration: none; color: inherit;
}
.cover-card:hover {
  transform: translateY(-3px); box-shadow: var(--shadow-hover);
  border-color: var(--accent-soft);
}
.cover-img-wrap {
  width: 100%; aspect-ratio: 16/9; background: linear-gradient(135deg, var(--bg-alt), var(--bg));
  position: relative; overflow: hidden;
}
.cover-img-wrap img { width: 100%; height: 100%; object-fit: cover; }
.cover-fallback {
  width: 100%; height: 100%; display: flex; align-items: center; justify-content: center;
  background: linear-gradient(135deg, var(--indigo), var(--accent));
}
.cover-fallback .code {
  font-family: var(--serif); font-size: 2.5rem; color: rgba(255,255,255,0.9); font-weight: 700;
}
.cover-body { padding: 16px 20px; }
.cover-body .code {
  font-family: var(--mono); font-size: 0.78rem; color: var(--accent); font-weight: 600;
}
.cover-body h4 { font-family: var(--serif); color: var(--indigo); margin: 6px 0 8px; font-size: 1.05rem; }
.cover-body .count { font-size: 0.82rem; color: var(--text-mute); }

/* ========== 倒计时 ========== */
.countdown-box { text-align: center; padding: 40px 20px; }
.countdown-display {
  display: flex; justify-content: center; gap: 24px; margin-bottom: 16px;
}
.countdown-display > span {
  font-family: var(--serif); font-size: 2.8rem; color: var(--accent); font-weight: 700;
  min-width: 1.2em; text-align: center;
}
.countdown-display small {
  font-size: 0.85rem; color: var(--text-mute); margin-left: 2px; margin-right: 4px;
}
.countdown-note { color: var(--text-mute); font-size: 0.92rem; }

/* ===== 视频缩略图卡片网格 ===== */
.video-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 18px;
}
.video-card {
  background: var(--bg-card);
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  overflow: hidden;
  cursor: pointer;
  transition: all .2s;
}
.video-card:hover {
  border-color: var(--accent);
  box-shadow: var(--shadow);
  transform: translateY(-2px);
}
.video-card:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
.video-thumb {
  position: relative;
  aspect-ratio: 16 / 9;
  background: #10131f;
  overflow: hidden;
}
.video-thumb img {
  width: 100%; height: 100%;
  object-fit: cover;
  display: block;
  transition: transform .25s;
}
.video-card:hover .video-thumb img { transform: scale(1.04); }
.video-thumb .thumb-fallback {
  width: 100%; height: 100%;
  display: flex; align-items: center; justify-content: center;
  background: linear-gradient(135deg, #c8553d, #d97742);
  color: #fff; font-size: 2rem;
}
.video-thumb .thumb-duration {
  position: absolute; right: 8px; bottom: 8px;
  background: rgba(0,0,0,.72); color: #fff;
  font-size: .72rem; padding: 2px 7px; border-radius: 5px;
  font-family: var(--mono);
}
.video-thumb .thumb-play {
  position: absolute; inset: 0;
  display: flex; align-items: center; justify-content: center;
  font-size: 2.4rem; color: rgba(255,255,255,.92);
  text-shadow: 0 2px 12px rgba(0,0,0,.55);
  background: rgba(0,0,0,.12);
  opacity: 0; transition: opacity .2s;
  pointer-events: none;
}
.video-card:hover .thumb-play { opacity: 1; }
.video-title {
  padding: 11px 13px 13px;
  font-size: .92rem; line-height: 1.45;
  color: var(--indigo); font-family: var(--serif);
  display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical;
  overflow: hidden;
  min-height: 2.9em;
}

/* ===== 视频放大播放层（弹窗） ===== */
.video-modal {
  position: fixed; inset: 0; z-index: 1000;
  display: none;
  align-items: center; justify-content: center;
  background: rgba(10, 12, 22, .82);
  padding: 24px;
}
.video-modal.open { display: flex; }
.video-modal-box {
  position: relative;
  width: 100%; max-width: 960px;
  background: #000;
  border-radius: 12px;
  overflow: hidden;
  box-shadow: 0 18px 60px rgba(0,0,0,.5);
}
.video-modal-box .player-wrap { position: relative; aspect-ratio: 16 / 9; }
.video-modal-box iframe {
  width: 100%; height: 100%;
  border: 0; display: block; background: #000;
}
.video-modal-close {
  position: absolute; top: 10px; right: 10px; z-index: 3;
  width: 34px; height: 34px;
  border: none; border-radius: 50%;
  background: rgba(255,255,255,.16); color: #fff;
  font-size: 1.1rem; line-height: 1; cursor: pointer;
  transition: background .15s;
}
.video-modal-close:hover { background: rgba(255,255,255,.32); }
/* 底部小字条 = 跳转 B 站的链接（整条可点击） */
.video-modal-hint {
  display: block;
  padding: 10px 14px;
  background: #10131f; color: rgba(255,255,255,.78);
  font-size: .82rem; text-align: center;
  text-decoration: none;
  transition: background .15s, color .15s;
}
.video-modal-hint:hover { background: #1a1f36; color: #8fb7ff; }

/* 工具入口卡（cover-card 变体，无封面图时显示大图标） */
.tool-card .cover-fallback span { font-size: 3rem; }
.tool-card .count { color: var(--text-mute); font-weight: 400; }

/* ===== 板块附属入口卡（播客/外部资源） ===== */
.link-cards {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 16px;
}
.link-card {
  display: flex; align-items: center; gap: 16px;
  background: var(--bg-card);
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  padding: 18px 20px;
  text-decoration: none;
  transition: all .2s;
}
.link-card:hover {
  border-color: var(--accent);
  box-shadow: var(--shadow);
  transform: translateY(-2px);
}
.link-card .link-code {
  flex-shrink: 0;
  width: 52px; height: 52px;
  border-radius: 12px;
  background: linear-gradient(135deg, #2d3a6b, #4a5a8c);
  color: #fff;
  display: flex; align-items: center; justify-content: center;
  font-family: var(--serif); font-size: 1.15rem;
}
.link-card .link-body { flex: 1; min-width: 0; }
.link-card .link-body b {
  display: block;
  font-family: var(--serif); font-size: 1.02rem;
  color: var(--indigo); margin-bottom: 3px;
}
.link-card .link-body small {
  color: var(--text-mute); font-size: .84rem; line-height: 1.45;
  display: block;
}
.link-card .link-arrow {
  color: var(--text-mute); font-size: 1.2rem;
  transition: transform .2s, color .2s;
}
.link-card:hover .link-arrow { color: var(--accent); transform: translateX(3px); }