Remove empty space at the top of Dribbblish

[the-argus]

Dribbblish has a gap at the top of the theme to make room for the overlapping window controls on Windows. This is not applicable on my linux system, where I use a tiling WM and don't even have window controls, much less overlapping ones. So this issue is up to some interpretation. The best solution would probably be to add some sort of option... (would be nice if I had used callPackage for the packages so we could get override, but that's out of scope of this issue). Alternatively, we could just confirm that the gap should be removed on KDE on linux (maybe confirm gnome as well, but I imagine it's the same) and then do it universally.

As for actually removing the gap, there is a CSS snippet out there somewhere, I'm pretty sure. I think I did it on arch before I ever used nix.