Decreasing height of Gallery:Masonary

Site URL: https://tuatara-onion-e66t.squarespace.com/

I'm wanting my homepage to have a splity screen, full bleed image gallery. I've acheieved that part, but I want the images to fit within the height of a desktop screen, currently they're too tall and I can't figure out how to adjust this. Image galleries dont have the same 'section height' option for some reason and I've tried multiple CSS suggestions from other threads but nothing has worked. 

site: https://tuatara-onion-e66t.squarespace.com/

pw.: snazzy

thanks in advance for any suggestions!