I hope I'm posting this in the right category...apologies if I chose wrong!

Is there a way to set the size of the popup window to no more than 800 px tall? Right now, when an author submits a book cover that's full-sized (1576x2522 or 1250x2000), the popup is huge...and doesn't automatically resize itself to screen height. I need to know how to set up the shopping cart so that, no matter how large the image is, the popup image is never larger than screen height.

Thanks!