How to theme lesson slide pages?

Hello! Thank you for your wonderful product, first of all! We are able to do amazing things with it! We are currently using a third party commercial theme with Opigno, which means we pretty much have to re-theme many parts of the system. One of the main one we need to re-theme is the lesson slide pages. I have scoured through the opigno theme folders and could not find which files are responsible for the following pages: slide, multiple choice, long answer, etc. Thank you in advance! Best, Ken