I'm not having any problems with the black background. The bullets/icons for unread threads are just barely visible because it's black, so it blends in. I suggest choosing another color.
Edit: I really like the new icons, I hope everyone else does as well. I really like how the colors turned out too. I went ahead and made all the icons a few pixels bigger than the older ones since it's 2012 and we all have decent resolution screens these days.