Tell us what’s happening:
I have passed all requirements, but it would look better if the nav bar was centered. I got it to center a few times, but then it no longer stayed at the top. Any suggestions?
Your nav-bar goes behind the video because you have given it fixed positioning. Since your nav element comes before your video element, the latter would be on top (think of it as a stack, newer elements come on top). To fix it, you can just add a z-index property on your nav-bar.