/* 关键CSS - 首屏渲染必需 */
body { margin: 0; font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif; }
.header { position: relative; z-index: 100; }
.main-content { min-height: 100vh; }
.loading { display: flex; justify-content: center; align-items: center; height: 200px; }
.loading::after { content: ''; width: 20px; height: 20px; border: 2px solid #f3f3f3; border-top: 2px solid #3498db; border-radius: 50%; animation: spin 1s linear infinite; }
@keyframes spin { 0% { transform: rotate(0deg); } 100% { transform: rotate(360deg); } }

/* 图片懒加载样式 */
img[data-src] { opacity: 0; transition: opacity 0.3s; }
img.loaded { opacity: 1; }
.lazy-placeholder { background: linear-gradient(90deg, #f0f0f0 25%, #e0e0e0 50%, #f0f0f0 75%); background-size: 200% 100%; animation: loading 1.5s infinite; }
@keyframes loading { 0% { background-position: 200% 0; } 100% { background-position: -200% 0; } }