Change background colour of product tiles and also expand them

How do I change the background colour of my product tiles to white? Right now they are the same colour as the background everywhere (greyish):

I would also like to extend the tiles a little so I can fit more than just the name and price on them. Like in this example:

I have a hard time finding where I change the code. In all the examples it says to go to Assets - Theme.Css.liquid but I have nothing there. Using a theme from Archetype.

Instead you can change the code directly in the Theme Settings under Custom CSS but it’s very limited characters. There must be another place to change the theme code in the actual code?

Hello!

You can make CSS changes from the section below. The designs you mentioned can be done manually. If you can provide the link to the site, I’ll try to help!

https://help.shopify.com/en/manual/online-store/themes/theme-structure/extend/add-css

Terence Keane

Best Regards,

Thank you!

its www.hillstone.se