Touch and Hold aka rollover on mobile for Dawn Theme 11

[Rambleroam]

Using Dawn 11 for new store. On desktop when showing a collection, you can rollover product images and it changes to the second image in the product. But it doesn't work on mobile. I saw another post that says this is called "touch and hold" for mobile--and the fixed offered up was pretty easy, but I dont have the same CSS files as what that post  can anyone tell me how to add that to my theme so mobile shows the second image? 

[ctrain]

I also need help with this! Can't find information anywhere..