From a usability design standpoint, Dark Green isn't the best choice for a black background (nor is light-grey text, but I digress). I got word a wile ago there is a re-design in the works but I don't know when that will happen or how it'll look.
If it really bugs you, you can use FireFox, and the extension GreaseMonkey
which will let you modify the colors (and layout if you want) of any individual site you visit. You need to know HTML, CSS and I believe some Javascritpt to take advantage of it though.
Or, again with Firefox you can use the EditCSS
plugin and load up a custom CSS file each time you visit.