2 Columns on mobile

Hello !

I would like to have automatic 2 columns for my products on my mobile phone. I use the template Symmetry 7.4.0. I don’t know for sure if I did find the right CCS file. I found Main collection liquid. Is this the right one? And what and where do I need to put an code?

So it has the options to show 2 columns, but I want that automaticly for the mobile.

Hope you guys can help me :slightly_smiling_face:

Lindsay