:root {
    /* Colors */
    --color-primary: #2563eb;
    --color-primary-dark: #1d4ed8;
    --color-primary-light: #dbeafe;
    --color-accent: #f59e0b;
    --color-accent-dark: #d97706;
    --color-accent-light: #fef3c7;
    --color-success: #10b981;
    --color-bg: #f8fafc;
    --color-surface: #ffffff;
    --color-text: #1e293b;
    --color-text-muted: #64748b;
    --color-text-light: #94a3b8;
    --color-border: #e2e8f0;
    --color-border-light: #f1f5f9;

    /* Typography
       Pure system-font stack: zero network calls, no IP leak to Google
       Fonts (which would trigger GDPR personal-data obligations).
       Latin fallback chain hits a clean sans on every major OS;
       CJK chain picks the OS's native Chinese face. */
    --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto,
                 'Helvetica Neue', Arial,
                 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei',
                 'Noto Sans CJK SC', 'Noto Sans SC', sans-serif;
    --font-mono: ui-monospace, 'SF Mono', Menlo, Monaco, Consolas,
                 'Liberation Mono', monospace;

    /* Sizing */
    --max-width: 1200px;
    --header-height: 64px;

    /* Spacing */
    --space-xs: 0.25rem;
    --space-sm: 0.5rem;
    --space-md: 1rem;
    --space-lg: 1.5rem;
    --space-xl: 2rem;
    --space-2xl: 3rem;
    --space-3xl: 4rem;
    --space-4xl: 6rem;

    /* Border radius */
    --radius-sm: 6px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 16px;
    --radius-full: 9999px;

    /* Shadows */
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.07), 0 2px 4px -2px rgba(0, 0, 0, 0.05);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.08), 0 4px 6px -4px rgba(0, 0, 0, 0.04);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 8px 10px -6px rgba(0, 0, 0, 0.04);

    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 250ms ease;
}