Black Text, White Background, as Gutenberg intended.
This is a repeat of a tip I got from BackupBrain. If you hate reading sites that use white text on who-knows-what color background, just drag this ("b/w") to your browser tool bar. Then when you visit such a site, all you have to do is click the b/w link in your Bookmarks Bar and web site will give you black text on a white background.(or, just click it now to see what happens.)