Update : Added a new CSS so that it works perfectly on most screen resolutions & the background shows its best when browser is resized..!! Give your Facebook login Page a Anonymous look..!! Looks pretty cool..!! Rate it..!! Connect with https://www.facebook.com/trickortips to stay updated..!! Google+ link http://www.goo.gl/GyJZB Follow me on twitter https://twitter.com/trickortips Also see :)
< Feedback on Anonymous Black Facebook Login Page
It's actually nice to have these available for those of us who don't want to install yet another extension.
Maybe try UserStyles?
Since this script doesn't do anything but inject new styles, it could easily be rewritten as a stylesheet for Stylish. https://userstyles.org/