/* 全局样式增强 */
.ui-style-1 {
  --primary-color: #3498db;
  --secondary-color: #2c3e50;
  --accent-color: #e74c3c;
  --bg-color: #f5f5f5;
  --text-color: #333;
}

/* 响应式优化 */
@media (max-width: 768px) {
  .container { padding: 15px; }
  h1 { font-size: 24px; }
  h2 { font-size: 20px; }
  .card-grid, .list-grid, .related-grid { grid-template-columns: 1fr; }
}

@media (max-width: 480px) {
  nav a { font-size: 12px; padding: 10px 6px; }
}

/* 动画效果 */
.card, .list-card, .related-card {
  animation: fadeInUp 0.5s ease-out;
}

@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* 返回顶部按钮 */
.back-to-top {
  position: fixed;
  bottom: 30px;
  right: 30px;
  background: var(--primary-color);
  color: white;
  width: 50px;
  height: 50px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  opacity: 0;
  transition: opacity 0.3s, transform 0.3s;
  z-index: 1000;
  box-shadow: 0 4px 12px rgba(0,0,0,0.2);
}

.back-to-top.show {
  opacity: 1;
}

.back-to-top:hover {
  transform: translateY(-4px);
  background: var(--secondary-color);
}