Portfolio mobile version shows drastically different spacing

I'm coming from adobe Muse, and so far I'm liking portfolio, but one thing I can't figure out is how to get the spacing consistent between the desktop and mobile versions. For instance, I'll set the spacing on a grid for the minimum spacing, and on the desktop it will appear around 1-2mm, but on the mobile version it will appear around 5-6mm or sometimes even more.

Note: I have not yet published a site. I am going off the preview in Adobe portfolio itself. Is it possible this is just a preview issue?