Hi Alisa,
RE: "FYI... does it weird anyone else out that the CSS applies to both the back-end and front-end? From a developer who has used a lot of CMSs, I find this to be incredibly bizarre. " - that's not what I understand by the concept of a Front and Back end whereby the UI is the front end (view) and the back end the database / model / controller, in MVC (Model View Controller). So with https://en.wikipedia.org/wiki/Front-end_web_development and https://en.wikipedia.org/wiki/Front_and_back_ends then CSS is always at the 'front end' and cannot be applied to the 'back end'. So I think you might be confused with the different views presented to users depending on their role. So in Wordpress there is the administration dashboard which is the UI to control things, however it still uses styles that are used for the site, such as font, heading and paragraph. Therefore Moodle is no different to any other CMS in this respect.
Gareth