Firstly, is that possible on a Wikia wiki? I have seen it on other wikis (don't remember on whether or not it was managed by Wikia).
Secondly, if it is, I have an idea for what the multiple themes would be. I have gone through the process of snapping the background images of each menu screen for each map (at 1920x1080@60Hz). The images are without actual menu elements ("loading..." text, menu options, etc.) and are directly screen-captured in the game. The themes would be named in accordance to what map they are based upon. So far, the only images I have are of Rainbow's, Snowman's, and Twilight's backgrounds.
Would this be a good idea if it is possible?