Hmm... Does this mean we can use Onsen as a 'drop in' replacement for the front end of an Ionic app? And simply rely on Ionic for the 'back end' routing etc.?

Hmm... Does this mean we can use Onsen as a 'drop in' replacement for the front end of an Ionic app? And simply rely on Ionic for the 'back end' routing etc.? I was just wondering if Onsen is mainly a set of CSS classes which could replace the Ionic ones for a different look and feel?