How can I make a gallery have different 'thumbnails per row' on desktop vs. mobile?

Site URL: https://bbaybrn.squarespace.com/

I'm referring to the client logo section in the homepage:

6 images per row looks best on desktop, but 3 per row would look best on mobile. (6 items gets much too small in that view)

What's the easiest way to achieve this? Thank you in advance for your time.

https://bbaybrn.squarespace.com/
PW: 123

Try adding this to Design > Custom CSS

@media screen and (max-width:767px) {
div#block-yui_3_17_2_1_1658008891303_675838 .slide {
    width: 33.3333% !important;
}
}