Simple white borders

Site URL: https://www.shannonturnercakes.com/

Site PW: stc2020

Can I add solid white borders around every image on this site? So the store images, the autoscrolling gallery on home page, the gallery image block buttons, etc. 

This is likely several codes. ?

I added a border once and deleted it because it was apparently bordering the full image instead of the crop. I hope that makes sense. Meaning part of the background was in between the image an the border. 

Any help appreciated!

Add to Home > Design > Custom CSS

img {
	border: 2px solid white;
}