Fixed IE7 CSS ugliness

Just fixed a bit of IE7-only CSS background b0rkeness in this blog theme. Thanks to Michael W. for pointing out the ugliness.

Because this is not my own theme -- and, okay, because it's IE, I'll admit it -- I just stuck a bit of IE7-specific hackery into the stylesheet. Apparently, "*:first-child+html" is still somehow valid CSS.

I would love to do a ground-up stylesheet for this blog without all the hacky legacy stuff. That'll be next on my list of largish projects, probably.