Yeah, Dan's thoughts about the CSS missing are automatically the first thing I think when I see a page load up like that. However, I remember that we disabled the "Always use Forum URL as Base Path" option. I just re-enabled it and the front page is working again. So apparently vBa CMPS (the front-page code) was having some sort of tantrum over the change. I'll leave it the way it is for now.
Stay safe, all of you out in the northeast US.