Hi there,

Welcome to your support management and thank you for choosing our theme!

You can use the following css code in order to manage the size of the single product image on smaller screens:

@media only screen and (max-width: 768px) {
    .eltd-single-product-images.images {
        width: 100%;
        padding: 0 5% 15px;
    }
}

Hope this helps! If there is anything else that we can help you with please don't hesitate to ask.

Kind regards,

Sean