Gallery Behavior on Mobile

I’d like to adjust the Gallery styling so that it doesn’t go to one image across on iPad and phone. Some of my galleries contain 50 images.

I notice that as you narrow the browser window, the images get smaller and then at a certain point they go to one image across. So I think I just need to adjust the CSS so that it goes to maybe 3 across on iPad, 2 across on phone.

https://wp.sonomasites.com/wp6/swatches/

Thank you in advance….