body.light-theme {
    --background: #f4f6fb;
    --surface: #ffffff;
    --surface-light: #eef1f7;
    --border: #d7dce7;

    --text: #111827;
    --muted: #64748b;

    --primary: #4f46e5;
    --primary-hover: #6366f1;
}

body.light-theme .cipher-box,
body.light-theme .rules-box,
body.light-theme .hint,
body.light-theme .difficulty-tabs {
    background: #f8fafc;
}