/* 全局样式 */
body.ui-style-13 {
  --primary-color: #1a73e8;
  --secondary-color: #34a853;
  --text-color: #333;
  --bg-color: #f5f5f5;
}

/* 响应式优化 */
@media (max-width: 768px) {
  nav .container {
    padding: 0 10px;
  }

  nav ul li a {
    padding: 12px 5px;
    font-size: 12px;
  }

  main {
    padding: 20px 15px !important;
  }

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

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

/* 卡片悬停效果 */
.video-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 4px 12px rgba(0,0,0,0.15) !important;
}

/* 导航激活状态 */
nav ul li a.active {
  color: var(--primary-color);
  font-weight: bold;
  border-bottom: 2px solid var(--primary-color);
}

/* 按钮样式 */
.btn {
  display: inline-block;
  padding: 10px 20px;
  background: var(--primary-color);
  color: #fff;
  border-radius: 4px;
  transition: all 0.3s;
}

.btn:hover {
  background: #1557b0;
  text-decoration: none;
}

/* 返回顶部按钮 */
#backToTop {
  position: fixed;
  bottom: 30px;
  right: 30px;
  background: var(--primary-color);
  color: #fff;
  width: 50px;
  height: 50px;
  border-radius: 50%;
  display: none;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  box-shadow: 0 2px 8px rgba(0,0,0,0.2);
  z-index: 999;
}

#backToTop:hover {
  background: #1557b0;
}