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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans SC", "Microsoft YaHei", sans-serif;
  line-height: 1.6;
  color: #333;
  background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
  min-height: 100vh;
}

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

header {
  background: rgba(255, 255, 255, 0.95);
  box-shadow: 0 2px 10px rgba(0,0,0,0.1);
  position: sticky;
  top: 0;
  z-index: 100;
}

.header-content {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 15px 20px;
  max-width: 1200px;
  margin: 0 auto;
}

.logo {
  font-size: 24px;
  font-weight: 700;
  color: #2c3e50;
  text-decoration: none;
}

nav {
  display: flex;
  flex-wrap: nowrap;
  align-items: center;
  gap: 5px;
}

nav a {
  padding: 8px 15px;
  color: #555;
  text-decoration: none;
  border-radius: 5px;
  transition: all 0.3s;
  white-space: nowrap;
  font-size: 15px;
}

nav a:hover {
  background: #3498db;
  color: white;
}

main {
  padding: 40px 0;
}

.section {
  background: white;
  border-radius: 10px;
  padding: 30px;
  margin-bottom: 30px;
  box-shadow: 0 3px 15px rgba(0,0,0,0.08);
}

h1 {
  font-size: 32px;
  color: #2c3e50;
  margin-bottom: 20px;
  line-height: 1.3;
}

h2 {
  font-size: 24px;
  color: #34495e;
  margin-bottom: 20px;
  padding-bottom: 10px;
  border-bottom: 3px solid #3498db;
}

h3 {
  font-size: 20px;
  color: #2c3e50;
  margin-bottom: 15px;
}

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

.video-card {
  background: #f8f9fa;
  border-radius: 8px;
  padding: 20px;
  transition: transform 0.3s, box-shadow 0.3s;
  border: 1px solid #e9ecef;
}

.video-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 5px 20px rgba(0,0,0,0.15);
}

.video-card h3 {
  margin-bottom: 10px;
}

.video-card h3 a {
  color: #2c3e50;
  text-decoration: none;
}

.video-card h3 a:hover {
  color: #3498db;
}

.video-meta {
  font-size: 14px;
  color: #7f8c8d;
  margin: 5px 0;
}

.video-desc {
  font-size: 14px;
  color: #555;
  margin-top: 10px;
  line-height: 1.5;
}

.video-tags {
  margin-top: 10px;
  display: flex;
  flex-wrap: wrap;
  gap: 5px;
}

.tag {
  display: inline-block;
  padding: 3px 10px;
  background: #e3f2fd;
  color: #1976d2;
  border-radius: 3px;
  font-size: 12px;
}

.intro-text {
  font-size: 16px;
  line-height: 1.8;
  color: #555;
  margin-bottom: 20px;
}

.detail-info {
  background: #f8f9fa;
  padding: 20px;
  border-radius: 8px;
  margin: 20px 0;
}

.detail-info p {
  margin: 10px 0;
  font-size: 15px;
  line-height: 1.8;
}

.detail-info strong {
  color: #2c3e50;
  display: inline-block;
  min-width: 80px;
}

.summary-box {
  background: #fff9e6;
  border-left: 4px solid #ffd700;
  padding: 20px;
  margin: 20px 0;
  border-radius: 5px;
}

.review-box {
  background: #e8f5e9;
  border-left: 4px solid #4caf50;
  padding: 20px;
  margin: 20px 0;
  border-radius: 5px;
}

footer {
  background: rgba(255, 255, 255, 0.9);
  padding: 30px 0;
  text-align: center;
  color: #7f8c8d;
  margin-top: 50px;
}

@media (max-width: 768px) {
  .header-content {
    flex-direction: column;
    gap: 10px;
    padding: 10px;
  }
  
  nav {
    width: 100%;
    justify-content: space-between;
    flex-wrap: nowrap !important;
    overflow: hidden;
  }
  
  nav a {
    flex: 1 1 0;
    min-width: 0;
    padding: 6px 5px;
    font-size: 13px;
    text-align: center;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
  }
  
  .video-grid {
    grid-template-columns: 1fr;
  }
  
  h1 {
    font-size: 24px;
  }
  
  h2 {
    font-size: 20px;
  }
}

body.ui-style-3 {
  --primary-color: #3498db;
  --secondary-color: #2ecc71;
}