/* 全局样式增强 */
main { animation: fadeIn 0.5s ease-in; }
@keyframes fadeIn {
  from { opacity: 0; transform: translateY(20px); }
  to { opacity: 1; transform: translateY(0); }
}

h1, h2, h3 { font-weight: 600; }

a { transition: color 0.3s; }
a:hover { color: #3498db; }

/* 响应式优化 */
@media (max-width: 768px) {
  main { padding: 0 0.8rem; }
  header h1 { font-size: 1.5rem; }
  article { padding: 1rem; }
}

/* 按钮样式 */
button, .btn {
  cursor: pointer;
  transition: all 0.3s;
  border: none;
  outline: none;
}

button:hover, .btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(0,0,0,0.15);
}

/* 卡片阴影 */
.card {
  box-shadow: 0 2px 8px rgba(0,0,0,0.08);
  transition: box-shadow 0.3s;
}

.card:hover {
  box-shadow: 0 4px 16px rgba(0,0,0,0.12);
}