/* ===== 曾鸣 AI课程知识图谱 - 共享样式 ===== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --bg: #ffffff;
  --dark: #1a1a2e;
  --mid: #16213e;
  --accent: #e94560;
  --blue: #0f3460;
  --blue-light: #1a5276;
  --gray: #6c757d;
  --gray-light: #f4f6f9;
  --border: #e0e4ef;
  --text: #2c3e50;
  --text-muted: #7f8c8d;
  --tag-core: #e94560;
  --tag-concept: #0f3460;
  --tag-case: #6c757d;
  --radius: 10px;
  --shadow: 0 2px 16px rgba(26,26,46,.08);
  --shadow-hover: 0 6px 32px rgba(26,26,46,.16);
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", "Hiragino Sans GB", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  font-size: 15px;
}

a { color: var(--blue); text-decoration: none; }
a:hover { color: var(--accent); }

/* ===== 导航 ===== */
nav {
  background: var(--dark);
  color: #fff;
  padding: 0 2rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 56px;
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: 0 2px 8px rgba(0,0,0,.2);
}
nav .logo {
  font-size: 1rem;
  font-weight: 700;
  color: #fff;
  display: flex;
  align-items: center;
  gap: .5rem;
}
nav .logo span { color: var(--accent); }
nav ul { list-style: none; display: flex; gap: 1.5rem; }
nav ul li a {
  color: rgba(255,255,255,.8);
  font-size: .9rem;
  transition: color .2s;
}
nav ul li a:hover, nav ul li a.active { color: #fff; }

/* ===== Hero ===== */
.hero {
  background: linear-gradient(135deg, var(--dark) 0%, var(--blue) 100%);
  color: #fff;
  padding: 5rem 2rem 4rem;
  text-align: center;
}
.hero h1 { font-size: 2.4rem; font-weight: 800; margin-bottom: 1rem; line-height: 1.3; }
.hero h1 span { color: var(--accent); }
.hero p { font-size: 1.1rem; opacity: .85; max-width: 640px; margin: 0 auto 2rem; }
.hero-meta { font-size: .85rem; opacity: .6; margin-top: .5rem; }

/* ===== 统计卡片 ===== */
.stats {
  display: flex;
  justify-content: center;
  gap: 1rem;
  flex-wrap: wrap;
  margin-top: 2.5rem;
}
.stat-card {
  background: rgba(255,255,255,.12);
  border: 1px solid rgba(255,255,255,.2);
  border-radius: var(--radius);
  padding: 1.2rem 2rem;
  text-align: center;
  min-width: 120px;
}
.stat-card .num { font-size: 2rem; font-weight: 800; color: var(--accent); }
.stat-card .label { font-size: .8rem; opacity: .75; margin-top: .2rem; }

/* ===== 按钮 ===== */
.btn {
  display: inline-block;
  padding: .65rem 1.5rem;
  border-radius: 6px;
  font-size: .9rem;
  font-weight: 600;
  cursor: pointer;
  transition: all .2s;
}
.btn-primary { background: var(--accent); color: #fff; }
.btn-primary:hover { background: #c73652; color: #fff; }
.btn-outline { border: 2px solid rgba(255,255,255,.5); color: #fff; }
.btn-outline:hover { border-color: #fff; background: rgba(255,255,255,.1); color: #fff; }
.hero-btns { display: flex; gap: 1rem; justify-content: center; flex-wrap: wrap; }

/* ===== 内容区 ===== */
.container { max-width: 1100px; margin: 0 auto; padding: 0 1.5rem; }
.section { padding: 3.5rem 0; }
.section-title {
  font-size: 1.5rem;
  font-weight: 800;
  color: var(--dark);
  margin-bottom: .4rem;
  display: flex;
  align-items: center;
  gap: .5rem;
}
.section-title::after {
  content: '';
  flex: 1;
  height: 2px;
  background: var(--border);
  margin-left: 1rem;
}
.section-sub { color: var(--text-muted); font-size: .9rem; margin-bottom: 2rem; }

/* ===== 概念卡片网格 ===== */
.cards-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1.2rem;
}
.card {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.4rem;
  box-shadow: var(--shadow);
  transition: all .25s;
  position: relative;
  overflow: hidden;
}
.card:hover {
  box-shadow: var(--shadow-hover);
  transform: translateY(-2px);
  border-color: var(--accent);
}
.card::before {
  content: '';
  position: absolute;
  top: 0; left: 0;
  width: 4px;
  height: 100%;
  background: var(--accent);
}
.card.concept::before { background: var(--blue); }
.card.case::before { background: var(--gray); }
.card-tag {
  display: inline-block;
  font-size: .72rem;
  font-weight: 700;
  padding: .2rem .6rem;
  border-radius: 4px;
  margin-bottom: .7rem;
  text-transform: uppercase;
  letter-spacing: .04em;
}
.tag-core { background: #ffeef1; color: var(--accent); }
.tag-concept { background: #eef4ff; color: var(--blue); }
.tag-case { background: #f4f4f4; color: var(--gray); }
.card h3 { font-size: 1.05rem; font-weight: 700; margin-bottom: .5rem; color: var(--dark); }
.card p { font-size: .88rem; color: var(--text-muted); line-height: 1.6; }
.card-link {
  display: inline-block;
  margin-top: .8rem;
  font-size: .82rem;
  color: var(--blue);
  font-weight: 600;
}
.card-link:hover { color: var(--accent); }

/* ===== 引用块 ===== */
blockquote {
  border-left: 4px solid var(--accent);
  background: var(--gray-light);
  padding: 1rem 1.4rem;
  border-radius: 0 var(--radius) var(--radius) 0;
  margin: 1.5rem 0;
  color: var(--text);
  font-style: italic;
}
blockquote cite {
  display: block;
  margin-top: .5rem;
  font-size: .8rem;
  color: var(--text-muted);
  font-style: normal;
}

/* ===== 详情页 ===== */
.detail-hero {
  background: linear-gradient(135deg, var(--dark) 0%, var(--blue) 100%);
  color: #fff;
  padding: 3rem 2rem;
}
.detail-hero .breadcrumb {
  font-size: .82rem;
  opacity: .7;
  margin-bottom: .8rem;
}
.detail-hero .breadcrumb a { color: rgba(255,255,255,.7); }
.detail-hero .breadcrumb a:hover { color: #fff; }
.detail-hero h1 { font-size: 2rem; font-weight: 800; margin-bottom: .5rem; }
.detail-hero .subtitle { font-size: 1rem; opacity: .8; }

.detail-body { max-width: 820px; margin: 0 auto; padding: 2.5rem 1.5rem; }
.detail-body h2 {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--dark);
  margin: 2rem 0 .8rem;
  padding-bottom: .4rem;
  border-bottom: 2px solid var(--border);
}
.detail-body p { margin-bottom: 1rem; color: var(--text); }
.detail-body ul, .detail-body ol {
  margin: .8rem 0 1rem 1.2rem;
  color: var(--text);
}
.detail-body li { margin-bottom: .4rem; }

.related-concepts { display: flex; flex-wrap: wrap; gap: .5rem; margin-top: .8rem; }
.related-tag {
  display: inline-block;
  padding: .3rem .8rem;
  border-radius: 20px;
  font-size: .82rem;
  background: var(--gray-light);
  color: var(--blue);
  border: 1px solid var(--border);
  transition: all .2s;
}
.related-tag:hover { background: var(--blue); color: #fff; }

/* ===== 图谱页 ===== */
#graph-container {
  width: 100%;
  height: calc(100vh - 56px);
  background: #0d1117;
  position: relative;
}
#graph-svg { width: 100%; height: 100%; }
.tooltip {
  position: absolute;
  background: rgba(255,255,255,.96);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: .8rem 1rem;
  font-size: .85rem;
  max-width: 220px;
  box-shadow: var(--shadow-hover);
  pointer-events: none;
  z-index: 99;
  display: none;
}
.tooltip strong { display: block; margin-bottom: .3rem; color: var(--dark); }
.tooltip span { color: var(--text-muted); font-size: .78rem; }
.graph-legend {
  position: absolute;
  bottom: 1.5rem;
  left: 1.5rem;
  background: rgba(13,17,23,.85);
  border: 1px solid rgba(255,255,255,.1);
  border-radius: 8px;
  padding: .8rem 1.2rem;
  color: #fff;
  font-size: .8rem;
}
.graph-legend h4 { margin-bottom: .5rem; opacity: .7; font-size: .75rem; text-transform: uppercase; letter-spacing: .05em; }
.legend-item { display: flex; align-items: center; gap: .5rem; margin-bottom: .3rem; }
.legend-dot { width: 10px; height: 10px; border-radius: 50%; flex-shrink: 0; }
.graph-tip {
  position: absolute;
  top: 1rem;
  left: 50%;
  transform: translateX(-50%);
  background: rgba(255,255,255,.1);
  color: rgba(255,255,255,.7);
  font-size: .78rem;
  padding: .4rem 1rem;
  border-radius: 20px;
  pointer-events: none;
}

/* ===== 标签列表 ===== */
.tag-cloud { display: flex; flex-wrap: wrap; gap: .5rem; margin-top: 1rem; }
.cloud-tag {
  display: inline-block;
  padding: .35rem .9rem;
  border-radius: 20px;
  font-size: .85rem;
  border: 1px solid var(--border);
  color: var(--text-muted);
  transition: all .2s;
  cursor: pointer;
}
.cloud-tag:hover { background: var(--dark); color: #fff; border-color: var(--dark); }
.cloud-tag.lg { font-size: 1rem; padding: .4rem 1.1rem; color: var(--dark); font-weight: 600; }
.cloud-tag.md { font-size: .9rem; }

/* ===== footer ===== */
footer {
  background: var(--dark);
  color: rgba(255,255,255,.5);
  text-align: center;
  padding: 2rem 1rem;
  font-size: .82rem;
  margin-top: 4rem;
}
footer a { color: rgba(255,255,255,.6); }
footer a:hover { color: #fff; }

/* ===== 时间线 ===== */
.timeline { position: relative; padding-left: 1.5rem; }
.timeline::before {
  content: '';
  position: absolute;
  left: 0; top: 0; bottom: 0;
  width: 2px;
  background: var(--border);
}
.timeline-item { position: relative; margin-bottom: 1.5rem; padding-left: 1rem; }
.timeline-item::before {
  content: '';
  position: absolute;
  left: -1.6rem; top: .4rem;
  width: 10px; height: 10px;
  border-radius: 50%;
  background: var(--accent);
  border: 2px solid #fff;
  box-shadow: 0 0 0 2px var(--accent);
}
.timeline-item h4 { font-size: .95rem; font-weight: 700; color: var(--dark); }
.timeline-item p { font-size: .87rem; color: var(--text-muted); margin-top: .2rem; }
.timeline-label {
  display: inline-block;
  font-size: .75rem;
  padding: .15rem .5rem;
  background: var(--gray-light);
  color: var(--gray);
  border-radius: 4px;
  margin-bottom: .4rem;
}

/* ===== 响应式 ===== */
@media (max-width: 640px) {
  .hero h1 { font-size: 1.7rem; }
  .stats { gap: .6rem; }
  .stat-card { padding: .8rem 1.2rem; min-width: 90px; }
  .stat-card .num { font-size: 1.5rem; }
  nav ul { gap: .8rem; }
  .cards-grid { grid-template-columns: 1fr; }
}