How can I display 3 products per row on mobile with the Brooklyn theme?

[jordontricks]

I'm using the Brooklyn theme and I would like to change my product selection page (inside of all collections) so that instead of being 1 product per row, there are 3 products in a row on mobile. I'm currently on grid instead of collage but making that change hasn't affected anything. Is there a bit of code that can help with this?

https://provada-jewelry.myshopify.com