/* 扩展样式 */
body.ui-style-3 {
  --primary-color: #667eea;
  --secondary-color: #764ba2;
}

.card, .list-item {
  transition: all 0.3s ease;
}

.card:hover {
  border-left: 4px solid var(--primary-color);
}

@media (max-width: 768px) {
  .grid {
    grid-template-columns: 1fr;
  }

  .main-nav ul {
    flex-wrap: nowrap !important;
    overflow-x: hidden;
  }
}

/* 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: none;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  box-shadow: 0 4px 12px rgba(0,0,0,0.2);
  transition: all 0.3s;
}

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

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