Prestige theme - aspect ratio of featured blog

[HollyHuxley]

Hi,

I'm wanting to change the aspect ratio of the featured blog on my homepage to 1:1 (square).
I am wondering what code I need to change to be able to do this?


Also I have 3 products listed under my homepage feature collections and the images are huge.
Am I able to make these smaller? Or the margins larger?

Appreciate any help!

Holly