Welcome to my hidden settings page! As per Changeblog #001, this was a big piece of functionality I was working towards, but abandoned in favor of a complete site overhaul I'm now chipping away at in the background so that this site stays a stable place for me to push out updates without being blocked by being in an in-between state.
I still chose to "publish" this page as a sort of "link only" page so that people like you and me can look at it later for reference for how something like this could be set up. For instance, one thing that took a lot of effort to work properly was to make the transition screen that appears whenever you change the theme or color scheme able to be interrupted (i.e. handle a user changing the scheme/theme mid-transition gracefully). The code is somewhat messy, but it's better than nothing!