G'day! (You guys speak French up there?)
i'm trying to get my head around how much of the front end development does foxy cart handle?
The FoxyCart payment page that the user then is taken to can be styled to look like your site. But you have to do that yourself. It's quite easy, but it's up to you to copy your design code and use it on the FoxyCart page too. Otherwise, the FoxyCart payment page would be just basic, unstyled HTML.