.product-info-popup .extra {
    display: flex;
}

.product-info-popup .extra div {
    width: 100%;
}

@media screen and (max-width: 768px) {
    .product-info-popup .extra{
        flex-direction: column;
    }
    .product-info-popup .section-optional-product-body td {
        width: 50%;
    }
}