If you use dark Windows themes this is an essential eye-saver Rated 4 out of 5 stars
Just what I needed. I would rather have something that modifies all white backgrounds only, but for now this will do. I like the fact that I can simply click a button to turn default styles back on when I can't see background images. Firefox/Cyberfox 33.
(Alternative: "I hate white" userscript -- works 50% of the time. If anyone knows of another please post it.) (Alternative2: The "Toolbar buttons" extension has a Toggle colours button.) Compatible with Firefox 33.