How do I disable product image cropping on Mobile?

Site URL: https://art.charlesstemen.com/

I'm selling photo prints.

On mobile my product images are being cropped on the store, product, and fullscreen preview page in a way where the user will never see the full product. Making white bars on the images that get cropped or putting an duplicate image into the additional info were suggestions I got from Squarespage support - so clunky haha, not what I am looking for... I get and am ok with the cropping on the store / product page, but it seems crazy to me that the fullscreen image would be cropped and not just responsively fit any size image to the width of the screen.

Whats frustrating is that if I switch from desktop to mobile while in the fullscreen image preview, it shows the image uncropped! So I can see it how I want it! But does not do this ever when on mobile/clicking into fullscreen preview from mobile, so not very helpful.

Is there some CSS I can add to remove image cropping on mobile/tablets for the fullscreen preview and potentially the product detail page entirely? Alternating between slideshow/stacked/carousel does not affect mobile appearance, and not seeing any other changes within Squarespace that would address this.  

Ive seen some other threads with similar topics, so maybe this is a lost cause..

It seems you solved with CSS?

May I ask, are you printing the art yourself or using an online service? Thanks a bunch!