Board Thread:Support Requests - Getting Technical/@comment-27625725-20160821061616

Hey everyone! Recently I noticed that the navigation bar image for a wiki I am an admin on(Lion King Fanon) appears different than I would like it to look. Instead of ending where the border of the navigation bar is, the image repeats, leaving a thick vertical line down the navigation bar. I'm not very good with this sort of thing; does anyone no how to fix it so that the image extends to the end of the page without repeating? 