:root {
    /* Y2K Millennium Palette (Circa 2008) */
    --color-bg-primary: #e8eef5;        /* 蓝调灰白背景 */
    --color-bg-secondary: #ffffff;      /* 白色卡片背景 */
    --color-bg-tertiary: #dde4ec;       /* 悬停态蓝灰 */
    
    --color-text-primary: #000000;      /* 纯黑文字 */
    --color-text-secondary: #4b4b4b;    /* 辅助文字 */
    --color-text-muted: #767676;        /* 弱化文字 */
    
    --color-accent: #1a56db;            /* Win7 亮蓝 - 经典链接与品牌色 */
    --color-accent-hover: #3b82f6;      /* 更亮的悬停蓝 */
    
    --color-danger: #cc0000;            /* 经典警告红 */
    --color-success: #008000;           /* 经典成功绿 */
    --color-warning: #ffcc00;           /* 警告黄 */
    
    --color-border: #a0a0a0;            /* 较深且硬朗的边框 */
    --color-overlay: rgba(0, 0, 0, 0.4);
    
    /* Y2K Typography */
    --font-family: Arial, Tahoma, Verdana, sans-serif;
    --font-size-xs: 11px;
    --font-size-sm: 12px;
    --font-size-base: 14px;
    --font-size-lg: 16px;
    --font-size-xl: 20px;
    --font-size-xxl: 24px;
    
    --line-height: 1.5;
    --font-weight-normal: 400;
    --font-weight-bold: 700;
    
    /* Y2K Spacing & Radius (Rougher look) */
    --space-xs: 4px;
    --space-sm: 8px;
    --space-md: 16px;
    --space-lg: 24px;
    --space-xl: 32px;
    
    --radius-sm: 4px;                   /* 小圆角 */
    --radius-md: 8px;                   /* 中圆角 */
    --radius-lg: 50%;                   /* 头像圆角 */
    --radius-xl: 12px;                  /* 大圆角 - 卡片与面板 */
    
    /* Y2K Shadows & Gradients */
    --shadow-card: 0 3px 8px rgba(0,0,0,0.15), 0 1px 2px rgba(0,0,0,0.1); /* 柔和 3D 阴影 */
    --shadow-modal: 0 8px 24px rgba(0,0,0,0.25), 0 2px 4px rgba(0,0,0,0.15);
    --shadow-nav: 0 2px 6px rgba(0,0,0,0.12);
    
    /* Y2K Skeuomorphic Effects */
    --shadow-skeuo-out: 2px 2px 0px #ffffff inset, -2px -2px 0px rgba(0,0,0,0.3) inset;
    --shadow-skeuo-in: -1px -1px 0px #ffffff inset, 1px 1px 0px rgba(0,0,0,0.3) inset;
    --border-skeuo: 2px solid;
    --border-skeuo-light: #ffffff #808080 #808080 #ffffff;
    --border-skeuo-dark: #808080 #ffffff #ffffff #808080;
    
    /* Frosted Glass Effects */
    --frosted-bg: rgba(220, 235, 255, 0.65);
    --frosted-border: rgba(255, 255, 255, 0.6);
    
    /* Glossy 3D Gradient */
    --gradient-3d: linear-gradient(135deg, rgba(255,255,255,0.4) 0%, rgba(255,255,255,0) 50%, rgba(0,0,0,0.1) 100%);
    --gradient-glossy: linear-gradient(180deg, rgba(255,255,255,0.3) 0%, rgba(255,255,255,0.05) 40%, transparent 50%, rgba(0,0,0,0.08) 100%);
}