Can you help me with this? It should stay collapsed, but somehow it doesn't. I believe that the problem is within the Navbox template, but I can't figure out what is it.
Try changing |state = collapsed
to |state = mw-collapsed
in the template you linked.
Another thing. I'm not sure how to fix the right sidebar. http://vampirediaries.wikia.com/wiki/The_Vampire_Diaries_Wiki
I think I fixed it.
I was about to say, its probably an unclosed tag.