requires http://freestyler.ws/style/103526/glass-every-single-part-of-firefox-3-5 , otherwise it makes all sites black with white text, green links and yellow visited links.
UPDATE: now with settings, you can change colors if you want.
If you use the glasser, it makes every page see-through. (now with a touch of red/blue/green - if wanted) I did this cause I didn't like the glass everything page from the same author cause of too much text shadow, and it simply didn't work. So I wanted something more simple, and came up with something quite simple.