Three Column Gird Layout in Mobile

Hi all,

I added this code snippet to create 2 columns to mobile on an account where I had previously adjusted so that it had 4 columns on desktop (per the instructions in section 3 of this post). I now find that, on desktop, if a search returns a number of cards not divisible by 4, the “extra” at the bottom of the results becomes extra wide (i.e., the width of 2 normal cards).

Any idea why this might be?

Thanks!
Ariana