/* ============================================
   CSS 变量系统
   ============================================ */

:root {
    /* 颜色系统 */
    --color-primary: #145895;
    --color-secondary: #c11b40;
    --color-text: #000;
    --color-text-light: #666;
    --color-text-muted: #777;
    --color-bg-overlay: rgba(255, 255, 255, 0.95);
    --color-link: #337ab7;
    --color-white: #fff;
    
    /* 间距系统 */
    --spacing-sm: 0.75rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    
    /* 字体大小 */
    font-size: 16px;
    
    /* 阴影 */
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 6px 16px rgba(0, 0, 0, 0.15);
    
    /* 圆角 */
    --radius-sm: 4px;
    --radius-md: 8px;
    
    /* 过渡时间 */
    --transition-base: 0.3s;
}

/* 暗色模式 */
@media (prefers-color-scheme: dark) {
    :root {
        --color-primary: #4a9eff;
        --color-secondary: #ff6b9d;
        --color-text: #e0e0e0;
        --color-text-light: #b0b0b0;
        --color-text-muted: #999;
        --color-bg-overlay: rgba(26, 26, 26, 0.95);
        --color-link: #5ba3ff;
    }
    
    /* 暗色模式下降低背景图片亮度 */
    .home-page,
    .about-page,
    .contact-page {
        position: relative;
    }
    
    .home-page::before,
    .about-page::before,
    .contact-page::before {
        content: '';
        position: absolute;
        top: 0;
        left: 0;
        right: 0;
        bottom: 0;
        background: rgba(0, 0, 0, 0.3);
        z-index: 0;
        pointer-events: none;
    }
    
    .home-page > *,
    .about-page > *,
    .contact-page > * {
        position: relative;
        z-index: 1;
    }
}