* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  line-height: 1.6;
  color: #333;
  background: #f5f5f5;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

.site-header {
  background: #fff;
  box-shadow: 0 2px 8px rgba(0,0,0,0.1);
  position: sticky;
  top: 0;
  z-index: 100;
}

.site-header .container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 15px 20px;
}

.logo {
  font-size: 24px;
  font-weight: bold;
  color: #2c3e50;
}

.main-nav {
  display: flex;
  gap: 25px;
  white-space: nowrap;
  overflow: visible;
}

.main-nav a {
  color: #555;
  text-decoration: none;
  font-weight: 500;
  transition: color 0.3s;
}

.main-nav a:hover,
.main-nav a.active {
  color: #3498db;
}

.main-content {
  min-height: 60vh;
  padding: 30px 0;
}

.hero-section {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
  padding: 60px 0;
  text-align: center;
}

.hero-title {
  font-size: 32px;
  font-weight: 600;
  line-height: 1.4;
}

.intro-section {
  background: white;
  padding: 40px 0;
  margin-bottom: 30px;
}

.intro-text {
  font-size: 16px;
  line-height: 1.8;
  color: #555;
  text-align: center;
  max-width: 900px;
  margin: 0 auto;
}

.home-section {
  margin-bottom: 50px;
}

.section-title {
  font-size: 26px;
  margin-bottom: 20px;
  color: #2c3e50;
  border-left: 4px solid #3498db;
  padding-left: 15px;
}

.video-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: 25px;
}

.video-grid.waterfall {
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
}

.video-card {
  background: white;
  border-radius: 12px;
  overflow: hidden;
  box-shadow: 0 4px 12px rgba(0,0,0,0.08);
  transition: transform 0.3s, box-shadow 0.3s;
}

.video-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 8px 24px rgba(0,0,0,0.15);
}

.video-card__link {
  display: block;
  text-decoration: none;
  color: inherit;
}

.video-cover {
  position: relative;
  width: 100%;
  padding-top: 56.25%;
  background: #e0e0e0;
  overflow: hidden;
}

.video-cover img {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.video-info {
  padding: 15px;
}

.video-title {
  font-size: 18px;
  font-weight: 600;
  margin-bottom: 8px;
  color: #2c3e50;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.video-one-line {
  font-size: 14px;
  color: #777;
  line-height: 1.5;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.page-header {
  background: white;
  padding: 30px;
  border-radius: 12px;
  margin-bottom: 30px;
}

.page-header h1 {
  font-size: 32px;
  color: #2c3e50;
  margin-bottom: 10px;
}

.page-desc {
  font-size: 16px;
  color: #666;
  line-height: 1.6;
}

.top-list__items {
  list-style: none;
}

.top-item {
  background: white;
  margin-bottom: 20px;
  border-radius: 12px;
  overflow: hidden;
  display: flex;
  align-items: center;
  box-shadow: 0 2px 8px rgba(0,0,0,0.08);
  transition: box-shadow 0.3s;
}

.top-item:hover {
  box-shadow: 0 4px 16px rgba(0,0,0,0.12);
}

.top-rank {
  background: #3498db;
  color: white;
  font-size: 24px;
  font-weight: bold;
  width: 60px;
  height: 80px;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.top-link {
  display: flex;
  flex: 1;
  text-decoration: none;
  color: inherit;
  padding: 15px;
  gap: 20px;
}

.top-cover {
  width: 120px;
  height: 80px;
  object-fit: cover;
  border-radius: 8px;
  flex-shrink: 0;
}

.top-info {
  flex: 1;
}

.top-title {
  font-size: 20px;
  font-weight: 600;
  margin-bottom: 5px;
  color: #2c3e50;
}

.top-meta {
  font-size: 14px;
  color: #999;
  margin-bottom: 5px;
}

.top-desc {
  font-size: 14px;
  color: #666;
  line-height: 1.5;
}

.video-player-section {
  background: #000;
  padding: 40px 0;
}

.video-player {
  max-width: 1000px;
  margin: 0 auto;
}

.video-player-inner {
  position: relative;
  width: 100%;
  padding-top: 56.25%;
  background: #111;
  border-radius: 12px;
  overflow: hidden;
}

.player-play-btn {
  position: absolute;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
  background: rgba(52,152,219,0.9);
  border: none;
  border-radius: 50%;
  width: 80px;
  height: 80px;
  cursor: pointer;
  transition: all 0.3s;
}

.player-play-btn:hover {
  background: rgba(52,152,219,1);
  transform: translate(-50%, -50%) scale(1.1);
}

.player-play-icon {
  color: white;
  font-size: 36px;
  display: block;
}

.detail-page {
  background: #f5f5f5;
}

.detail-header {
  background: white;
  padding: 30px 0;
  border-bottom: 1px solid #eee;
}

.detail-title {
  font-size: 36px;
  font-weight: 700;
  color: #2c3e50;
}

.detail-info {
  background: white;
  padding: 30px 0;
  margin-bottom: 20px;
}

.info-title {
  font-size: 24px;
  margin-bottom: 20px;
  color: #2c3e50;
}

.info-list {
  display: grid;
  grid-template-columns: 100px 1fr;
  gap: 15px;
  font-size: 16px;
}

.info-list dt {
  font-weight: 600;
  color: #555;
}

.info-list dd {
  color: #666;
}

.detail-module {
  background: white;
  padding: 30px;
  margin-bottom: 20px;
  border-radius: 12px;
}

.module-title {
  font-size: 22px;
  margin-bottom: 15px;
  color: #2c3e50;
  border-left: 4px solid #3498db;
  padding-left: 12px;
}

.module-content {
  font-size: 16px;
  line-height: 1.8;
  color: #555;
}

.related-section {
  margin-top: 40px;
  padding: 30px 0;
  background: white;
}

.site-footer {
  background: #2c3e50;
  color: white;
  text-align: center;
  padding: 30px 0;
  margin-top: 50px;
}

body.ui-style-4 {
  background: #fafafa;
}

body.ui-style-4 .hero-section {
  background: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
}

body.ui-style-4 .main-nav a.active,
body.ui-style-4 .main-nav a:hover {
  color: #00b4d8;
}

body.ui-style-4 .video-card:hover {
  box-shadow: 0 8px 20px rgba(0,180,216,0.3);
}

@media (max-width: 768px) {
  .main-nav {
    gap: 15px;
    font-size: 14px;
  }

  .logo {
    font-size: 20px;
  }

  .hero-title {
    font-size: 24px;
  }

  .video-grid {
    grid-template-columns: repeat(auto-fill, minmax(150px, 1fr));
    gap: 15px;
  }

  .video-grid.waterfall {
    grid-template-columns: 1fr 1fr;
  }

  .video-cover {
    padding-top: 60%;
  }

  .video-title {
    font-size: 16px;
  }

  .top-rank {
    width: 50px;
    height: 60px;
    font-size: 20px;
  }

  .top-cover {
    width: 80px;
    height: 60px;
  }

  .top-link {
    padding: 10px;
    gap: 10px;
  }

  .detail-title {
    font-size: 28px;
  }

  .info-list {
    grid-template-columns: 80px 1fr;
    gap: 10px;
    font-size: 14px;
  }
}