:root {
    /* spacing */
    --space-1: 4px;
    --space-2: 8px;
    --space-3: 12px;
    --space-4: 16px;
    --space-5: 24px;
    --space-6: 32px;

    /* radius */
    --radius-sm: 6px;
    --radius-md: 10px;
    --radius-lg: 16px;

    /* animation */
    --ease-default: cubic-bezier(0.4, 0, 0.2, 1);
    --transition-fast: 150ms var(--ease-default);
    --transition-base: 250ms var(--ease-default);

    /* layout */
    --max-width: 1200px;
}

:root[data-theme="light"] {
    --color-bg: #ffffff;
    --color-bg-sub: #f9fafb;
    --color-surface: #ffffff;

    --color-text: #111827;
    --color-text-muted: #6b7280;

    --color-border: #e5e7eb;
    --color-accent: #2563eb;
    --color-accent-hover: #1d4ed8;

    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.04);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.08);
}

:root[data-theme="dark"] {
    --color-bg: #0f172a;
    --color-bg-sub: #020617;
    --color-surface: #111827;

    --color-text: #e5e7eb;
    --color-text-muted: #9ca3af;

    --color-border: #1f2937;
    --color-accent: #60a5fa;
    --color-accent-hover: #3b82f6;

    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.4);
    --shadow-md: 0 6px 20px rgba(0, 0, 0, 0.5);
}

body {
    background-color: var(--color-bg);
    color: var(--color-text);
    transition:
        background-color var(--transition-base),
        color var(--transition-base);
}