Add small space/gap between images in "Gallery Grid: Masonry" (7.1)

Site URL: https://elk-robin-3ckg.squarespace.com/

Hi,

I'm trying to build my image portfolio using the "Gallery Grid:Masonry" on a blank page and then I link the gallery images to different projects in "hidden (NOT LINKED) "Portfolio pages". This seems to work very well, some extra steps involved, but this way I'm not limited to 40 images in a single portfolio.

I have added two portfolio links to header menu for testing — "Portfolio" and "Portfolio 1". The first link ("Portfolio") uses the 'Gallery:Masonry' (the one I will use)  and the second ("portfolio 1") uses the standard 'Portfolio page'.

I want the same small space between the thumbnails in my gallery grid, so it matches the look on the "Portfolio1" page. How do I do this?

Link to test website https://elk-robin-3ckg.squarespace.com/

I have experimented with some CSS from this forum, so I'm not sure if there are codes that interfer with each other.. I want to keep the zoom and overlay effects.

Thanks!