I can't figure out how to get portfolio grids (or any grid for that matter) to collapse with a shrinking viewport like in the Reframe + demo site: https://northeme.com/theme-live/reframe-plus

For example, here is a three column grid that I would like to collapse as I shrink the screen. It stays in 3 columns no matter how narrow the browser window and I cannot find the fix.

http://www.feather2pixels.com/turntable/

thanks!

Jon