Change header height

I'm having some trouble setting the header height of this theme. Currently the home page has a proper full-screen height with my logo and all, but the header height on different pages seems to be abnormally large, causing a large "blank" header portion. As you can see on this page of my website, the height of the header is quite large and I would like to reduce it, so it's closer to the height of the menu. So far I've tried a couple of things, but I can't seem to find a setting that does what I want. Is it possible to change this height and if so, how?