Thumbnail view not responsive

I can’t seem to find a configuration that will make this gallery responsive. The site itself, and all the other elements, behaves properly, but the thumbnails in the gallery force themselves out beyond the margins on phones and tablets.

The settings include absolute numbers for image width and number of columns, but I know it’s supposed to be responsive, so that seems contradictory. Do I need to create custom media queries and CSS?

Any help greatly appreciated.

The gallery is halfway down the page, where all the sample wheels are.

The page I need help with: [log in to see the link]