@media (max-width: 600px) {
    .grid {
        grid-template-columns: repeat(4, 70px);
        grid-template-rows: repeat(4, 70px);
        gap: 8px;
    }
    .cell {
        font-size: 24px;
    }
    .btn {
        width: 55px;
        height: 55px;
        font-size: 24px;
    }
    .modal-content {
        padding: 20px 25px;
        font-size: 22px;
        min-width: 260px;
    }
    .modal-btn {
        padding: 8px 18px;
        font-size: 16px;
    }
}