/* 共享视觉语言：跨 落地页 / 2b / 4b / mm 四个页面复用。
   设计参考 https://spaces.ac.cn/me.html 的时间线（空心圆点+竖线）与深色顶栏卡片式布局，
   但改成更克制的现代配色，不用衬线字体。 */

:root {
  --page-bg: #eef0f3;
  --card-bg: #ffffff;
  --border: #e5e7eb;
  --text: #111827;
  --text-secondary: #6b7280;
  --text-tertiary: #9ca3af;
  --header-bg: #161b25;
  --header-bg-2: #1f2637;
  --accent: #4f7cff;
  --e1: #2563eb;
  --e2: #d97706;
  --e3: #059669;
  --e4: #9333ea;
  --e5: #db2777;
  --danger: #dc2626;
  --info-bg: #eff6ff;
  --info-border: #bfdbfe;
  --tl-green: #66cd00;
}
* { box-sizing: border-box; }
html, body {
  margin: 0;
  background: var(--page-bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
  line-height: 1.5;
}

/* ---- 顶栏：深色，跨页面一致，用于站内导航 ---- */
.site-header {
  background: linear-gradient(135deg, var(--header-bg), var(--header-bg-2));
  color: #f3f4f6;
}
.site-header-inner {
  max-width: 1160px;
  margin: 0 auto;
  padding: 16px 24px;
  display: flex;
  align-items: center;
  gap: 24px;
}
.site-brand {
  font-size: 15px;
  font-weight: 650;
  color: #fff;
  text-decoration: none;
  white-space: nowrap;
}
.site-brand .dot { color: var(--tl-green); }
.site-nav {
  display: flex;
  gap: 4px;
  flex-wrap: wrap;
}
.site-nav a {
  color: rgba(255,255,255,0.72);
  text-decoration: none;
  font-size: 13px;
  font-weight: 550;
  padding: 7px 12px;
  border-radius: 7px;
  transition: background 0.12s, color 0.12s;
}
.site-nav a:hover { color: #fff; background: rgba(255,255,255,0.08); }
.site-nav a.active { color: #fff; background: rgba(255,255,255,0.14); }

/* ---- 页面外框：浅灰底 + 居中白卡片 ---- */
.page-shell {
  max-width: 1160px;
  margin: 28px auto 80px;
  padding: 0 24px;
}
.page-card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 32px 36px 44px;
  box-shadow: 0 1px 2px rgba(16,24,40,0.04), 0 1px 12px rgba(16,24,40,0.03);
}

/* ---- 落地页 track 卡片 ---- */
.track-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 18px;
  margin-top: 20px;
}
@media (max-width: 900px) { .track-grid { grid-template-columns: 1fr; } }
.track-card {
  display: block;
  text-decoration: none;
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 20px 20px 18px;
  transition: transform 0.12s, box-shadow 0.12s, border-color 0.12s;
  position: relative;
  overflow: hidden;
}
.track-card:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 20px rgba(16,24,40,0.08);
  border-color: #d1d5db;
}
.track-card .bar { position: absolute; left: 0; top: 0; bottom: 0; width: 4px; }
.track-card .kicker { font-size: 11.5px; color: var(--text-tertiary); text-transform: uppercase; letter-spacing: 0.04em; font-weight: 650; }
.track-card h3 { font-size: 17px; margin: 4px 0 8px; }
.track-card p.desc { font-size: 13px; color: var(--text-secondary); margin: 0 0 14px; min-height: 54px; }
.track-card .stat-row { display: flex; gap: 14px; font-size: 12px; color: var(--text-tertiary); border-top: 1px solid var(--border); padding-top: 10px; }
.track-card .stat-row b { color: var(--text); font-weight: 650; }
.track-card .go { position: absolute; right: 18px; top: 18px; font-size: 12px; color: var(--accent); font-weight: 650; }

/* ---- 时间线（借鉴 spaces.ac.cn 的"微言微语"：空心圆点+竖线） ---- */
.timeline { position: relative; margin: 6px 0 0; padding-left: 6px; }
.timeline::before {
  content: "";
  position: absolute;
  left: 96px;
  top: 6px;
  bottom: 6px;
  width: 1px;
  background: var(--border);
}
.tl-row { display: flex; align-items: flex-start; gap: 18px; padding: 10px 0; position: relative; }
.tl-date { width: 78px; flex: none; text-align: right; font-size: 12px; color: var(--text-tertiary); padding-top: 2px; font-variant-numeric: tabular-nums; }
.tl-bullet {
  width: 12px; height: 12px; border-radius: 50%;
  background: #fff; border: 2px solid var(--tl-green);
  flex: none; margin-top: 3px; position: relative; z-index: 1;
}
.tl-bullet.grey { border-color: #c7cbd1; }
.tl-bullet.amber { border-color: #d97706; }
.tl-desc { font-size: 13.5px; color: var(--text); line-height: 1.6; padding-top: 1px; }
.tl-desc .tag {
  display: inline-block;
  font-size: 11px;
  font-weight: 650;
  padding: 1px 7px;
  border-radius: 5px;
  margin-right: 6px;
  color: #fff;
  vertical-align: 1px;
}

/* ---- 状态徽标（复用于落地页/子页面） ---- */
.status-pill { display: inline-flex; align-items: center; gap: 5px; font-size: 12px; font-weight: 600; padding: 3px 9px; border-radius: 999px; }
.status-pill .sdot { width: 6px; height: 6px; border-radius: 50%; display: inline-block; }
.status-pill.done { background: #ecfdf5; color: #047857; }
.status-pill.done .sdot { background: #059669; }
.status-pill.running { background: #fffbeb; color: #b45309; }
.status-pill.running .sdot { background: #d97706; }
.status-pill.planned { background: #f3f4f6; color: #4b5563; }
.status-pill.planned .sdot { background: #9ca3af; }

.footer-note {
  max-width: 1160px;
  margin: 0 auto 40px;
  padding: 0 24px;
  color: var(--text-tertiary);
  font-size: 12px;
}
.footer-note a { color: var(--text-secondary); }

/* 算法介绍页二级导航：算法 / 多模态 */
.algo-subnav {
  display: flex;
  gap: 4px;
  flex-wrap: wrap;
  border-bottom: 1px solid var(--border);
  margin: 4px 0 24px;
}
.algo-subnav a {
  text-decoration: none;
  color: var(--text-secondary);
  font-size: 14px;
  font-weight: 550;
  padding: 10px 16px;
  margin-bottom: -1px;
  border-bottom: 2px solid transparent;
}
.algo-subnav a:hover { color: var(--text); }
.algo-subnav a.active {
  color: var(--text);
  border-bottom-color: var(--text);
}