body.ui-style-7 {
  --primary-color: #3498db;
  --secondary-color: #2ecc71;
  --accent-color: #e74c3c;
  --text-color: #2c3e50;
  --bg-gradient-start: #f5f7fa;
  --bg-gradient-end: #c3cfe2;
}

main {
  padding: 40px 0;
  min-height: calc(100vh - 200px);
}

section {
  background: white;
  border-radius: 12px;
  padding: 30px;
  margin-bottom: 30px;
  box-shadow: 0 4px 20px rgba(0,0,0,0.08);
  transition: transform 0.3s, box-shadow 0.3s;
}

section:hover {
  transform: translateY(-5px);
  box-shadow: 0 6px 30px rgba(0,0,0,0.12);
}

h1 {
  font-size: 32px;
  color: var(--text-color);
  margin-bottom: 20px;
  text-align: center;
  font-weight: 700;
}

h2 {
  font-size: 26px;
  color: var(--primary-color);
  margin-bottom: 20px;
  padding-bottom: 10px;
  border-bottom: 3px solid var(--secondary-color);
}

h3 {
  font-size: 20px;
  color: var(--text-color);
  margin: 15px 0 10px;
}

p {
  margin-bottom: 15px;
  line-height: 1.8;
}

.intro-section {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
}

.intro-section h1,
.intro-section p {
  color: white;
}

.video-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 25px;
  margin-top: 20px;
}

.video-card {
  background: #fff;
  border-radius: 10px;
  padding: 20px;
  box-shadow: 0 2px 10px rgba(0,0,0,0.08);
  transition: all 0.3s;
  border-left: 4px solid var(--primary-color);
}

.video-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 8px 25px rgba(0,0,0,0.15);
  border-left-color: var(--accent-color);
}

.video-card h3 {
  color: var(--primary-color);
  margin-bottom: 10px;
  font-size: 18px;
}

.video-card .meta {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin: 10px 0;
  font-size: 13px;
  color: #666;
}

.video-card .meta span {
  background: #f0f0f0;
  padding: 3px 10px;
  border-radius: 12px;
}

.video-card .desc {
  color: #555;
  font-size: 14px;
  line-height: 1.6;
  margin: 10px 0;
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.video-card a {
  display: inline-block;
  margin-top: 10px;
  padding: 8px 20px;
  background: var(--primary-color);
  color: white;
  text-decoration: none;
  border-radius: 20px;
  transition: background 0.3s;
}

.video-card a:hover {
  background: var(--accent-color);
}

.video-list {
  list-style: none;
}

.video-list li {
  padding: 20px;
  border-bottom: 1px solid #eee;
  transition: background 0.3s;
}

.video-list li:hover {
  background: #f9f9f9;
}

.video-list li:last-child {
  border-bottom: none;
}

.video-list h3 {
  font-size: 18px;
  margin-bottom: 10px;
}

.video-list .meta {
  color: #888;
  font-size: 13px;
  margin: 8px 0;
}

.video-list .desc {
  color: #555;
  line-height: 1.7;
  margin: 10px 0;
}

.video-list a {
  color: var(--primary-color);
  text-decoration: none;
  font-weight: 500;
}

.video-list a:hover {
  text-decoration: underline;
}

.detail-header {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
  padding: 40px;
  border-radius: 12px;
  margin-bottom: 30px;
}

.detail-header h1 {
  color: white;
  font-size: 36px;
  margin-bottom: 20px;
}

.detail-meta {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: 15px;
  margin: 20px 0;
}

.detail-meta-item {
  background: rgba(255,255,255,0.1);
  padding: 15px;
  border-radius: 8px;
}

.detail-meta-item strong {
  display: block;
  margin-bottom: 5px;
  opacity: 0.9;
}

.tags {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin: 15px 0;
}

.tag {
  background: var(--secondary-color);
  color: white;
  padding: 5px 15px;
  border-radius: 15px;
  font-size: 13px;
}

.content-section {
  margin: 30px 0;
}

.content-section h2 {
  color: var(--primary-color);
  margin-bottom: 15px;
}

.related-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: 20px;
  margin-top: 20px;
}

.related-card {
  background: #f9f9f9;
  padding: 20px;
  border-radius: 10px;
  border-left: 3px solid var(--primary-color);
  transition: all 0.3s;
}

.related-card:hover {
  background: white;
  box-shadow: 0 4px 15px rgba(0,0,0,0.1);
  border-left-color: var(--accent-color);
}

.related-card h4 {
  color: var(--text-color);
  margin-bottom: 10px;
  font-size: 16px;
}

.related-card p {
  color: #666;
  font-size: 14px;
  line-height: 1.6;
  margin-bottom: 10px;
}

.related-card a {
  color: var(--primary-color);
  text-decoration: none;
  font-size: 14px;
}

.related-card a:hover {
  text-decoration: underline;
}

.back-to-top {
  position: fixed;
  bottom: 30px;
  right: 30px;
  width: 50px;
  height: 50px;
  background: var(--primary-color);
  color: white;
  border: none;
  border-radius: 50%;
  cursor: pointer;
  display: none;
  align-items: center;
  justify-content: center;
  font-size: 20px;
  box-shadow: 0 4px 15px rgba(0,0,0,0.2);
  transition: all 0.3s;
}

.back-to-top:hover {
  background: var(--accent-color);
  transform: translateY(-5px);
}

.back-to-top.visible {
  display: flex;
}

@media (max-width: 768px) {
  h1 {
    font-size: 24px;
  }

  h2 {
    font-size: 20px;
  }

  section {
    padding: 20px;
  }

  .video-grid {
    grid-template-columns: 1fr;
    gap: 15px;
  }

  .detail-header {
    padding: 25px;
  }

  .detail-header h1 {
    font-size: 26px;
  }

  .detail-meta {
    grid-template-columns: 1fr;
  }

  .related-grid {
    grid-template-columns: 1fr;
  }
}

.list-header {
  background: white;
  padding: 30px;
  border-radius: 12px;
  margin-bottom: 30px;
  text-align: center;
}

.list-intro {
  color: #666;
  line-height: 1.8;
  margin-top: 15px;
}

.ranking-number {
  display: inline-block;
  width: 30px;
  height: 30px;
  line-height: 30px;
  text-align: center;
  background: var(--primary-color);
  color: white;
  border-radius: 50%;
  margin-right: 10px;
  font-weight: bold;
}

.topic-tag {
  display: inline-block;
  background: var(--secondary-color);
  color: white;
  padding: 4px 12px;
  border-radius: 12px;
  font-size: 12px;
  margin-right: 8px;
  margin-bottom: 8px;
}

.update-date {
  color: #999;
  font-size: 13px;
  margin-top: 8px;
}