Centering Marketpress Product List Widget Thumbnails

I'm attempting to adjust the CSS for the Marketpress Product List Widget that is displaying Thumbnails. I'm hoping to show 3 products in a row, and not only center them but allow for equal spacing between the products in the block – all while maintaining the responsivitiy of the site... :slight_smile:

Any ideas??

Please see the site here: http://amp.group218.com/

Thank you!

brad