BigCommerce Product Layout Revamp

I need a set of precise CSS edits applied to my current BigCommerce theme so the catalogue pages look clean and consistent in every view. I can not allow anyone in the backend so you'll need to do your best to identify what files to update, I can send you a screenshot of the hierarchy or any other suggestion.

First Item
When we add more than 5 pictures, the thumbnail format changes, example:
https://theemcshop.com/near-field-probes-e-h/langer-emv-rf-e-e-field-probe-series/

Second Item
Product Listing Pages (see attached screenshots) - the border of the product cards needs to be dark like the sub category thumbs, both H2 tabs need padding/margin on top and bottom. The left alignment of subcategories and products is also off.