Hi there I am trying to achieve the same effect for one page of my website as well. I want to keep the mobile site how it is, except for one page where I am trying to have 2 or 3 columns (rather than one).
the site is under: https://opossum-amphibian-zl2f.squarespace.com
and the specific page I want one than one column for is the archive page: https://opossum-amphibian-zl2f.squarespace.com/archive
Please let me know if you have any solutions! Thanks!