I just, I just don't know what I'm doing wrong and I don't want to break the wiki. I've been experimenting with the Media wiki by trying to edit infobox's color, but nothing is changing. I've read the articles to the best of my ability, but I'm not sure what it is that's not happening. I've also heard about pi europa? Is that necessary?
The europa theme would only matter if it is enabled on your wiki. Could you link to an example page so we can see what is going on? There are no errors in your posted CSS however, there are other reasons it may not be working.