/* 全局样式增强 */
.video-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 4px 12px rgba(0,0,0,0.15) !important;
}

.video-card h3 a:hover {
  color: #e74c3c !important;
}

.ranking-item:hover {
  background: #f9f9f9;
}

nav a.active {
  color: #e74c3c;
  font-weight: bold;
}

/* 响应式优化 */
@media (max-width: 768px) {
  .video-grid {
    grid-template-columns: 1fr !important;
  }

  .hero {
    padding: 20px !important;
  }

  h1 {
    font-size: 24px !important;
  }

  .ranking-item {
    flex-direction: column;
    align-items: start !important;
  }

  .rank-num {
    width: auto !important;
    margin-bottom: 10px;
  }
}

/* 动画效果 */
a {
  transition: all 0.3s ease;
}

.video-card, .ranking-item, .topic-group > div > div {
  transition: all 0.3s ease;
}

/* UI 风格变体 */
.ui-style-3 {
  --primary-color: #e74c3c;
  --secondary-color: #3498db;
}

/* 返回顶部按钮 */
#back-to-top {
  position: fixed;
  bottom: 30px;
  right: 30px;
  width: 50px;
  height: 50px;
  background: #e74c3c;
  color: #fff;
  border: none;
  border-radius: 50%;
  font-size: 20px;
  cursor: pointer;
  display: none;
  z-index: 999;
  transition: all 0.3s;
}

#back-to-top:hover {
  background: #c0392b;
  transform: scale(1.1);
}

#back-to-top.show {
  display: block;
}