/* 响应式设计 */
@media (max-width: 768px) {
body { padding: 12px; }
header { padding: 12px 16px; flex-direction: column; }
.container { max-width: 100%; padding: 0 8px; }
h1 { font-size: 1.5rem; }
textarea, input, select, button { width: 100%; }
.grid { grid-template-columns: 1fr; }
.card { padding: 12px; }
}