/* 关键CSS - 首屏渲染必需的样式 */
/* 这些样式应该内联到 HTML head 中以加速首屏渲染 */

:root {
    /* 基础颜色变量 */
    --primary-color: #0066cc;
    --text-color: #1a1a1a;
    --bg-color: #ffffff;
    --border-color: #e1e4e8;
}

/* 基础布局 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--bg-primary);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* 容器 */
.app {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* 头部 */
.header {
    position: sticky;
    top: 0;
    z-index: 100;
    background: var(--bg-primary);
    border-bottom: 1px solid var(--border-color);
}

.header-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

/* 主内容区 */
.main {
    flex: 1;
    padding: 2rem 0;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
}

/* 图片懒加载占位符 */
img[loading="lazy"] {
    opacity: 0;
    transition: opacity 0.3s ease-in;
}

img[loading="lazy"].loaded {
    opacity: 1;
}

/* 骨架屏效果 */
.skeleton {
    background: linear-gradient(90deg, #f0f0f0 25%, #e0e0e0 50%, #f0f0f0 75%);
    background-size: 200% 100%;
    animation: skeleton-loading 1.5s infinite;
}

@keyframes skeleton-loading {
    0% {
        background-position: 200% 0;
    }
    100% {
        background-position: -200% 0;
    }
}

/* 性能优化：减少重绘 */
.post-card {
    will-change: transform;
    transform: translateZ(0);
}

/* 性能优化：GPU 加速 */
.theme-btn,
.action-btn {
    transform: translateZ(0);
    backface-visibility: hidden;
}