One of the best inventions since the www itself! Rated 5 out of 5 stars
Fluently lets me enjoy blinding white pages again by offering me styles that are dark! Never a problem if you carefully pick the well-maintained userstyles.
Those people rating this with one star must be insane or have lost their minds! This is one of the best Add-Ons that ever surfaced for Firefox. Works fluently for many websites, with a huge amount of choice and offerings and no performance hit whatsoever: http://userstyles.org/