Problems with nav bar

I’m having difficulties getting my links within the nav bar to have the same height as the black nav bar. When I hover over one of the links, it’s blue and there is a black border on the top and bottom. If I set padding: 0px for .nav (see L74 of this gist) then I get a white border between the header and the nav bar. If I do that I also get a “rough” edge along the bottom of the nav bar.