I think I've finally managed to center this layout without everything moving around when zooming in/out, but I'm not sure how it'll look on other resolutions. I feel like it ended up looking worse than what I had originally but I don't really have the energy to work on this anymore.
I really wanted to center this layout but I could not for the life of me get the nav and content sections to stop shifting around when zooming into a page...so this will have to do for now. (I don't want all of my fansite themes to look the same but I also want to keep this as fun and stress-free as possible!) I'm most excited to work on this fansite. There needs to be more hours in the day...