Nice work. I love the ability to adjust the background (and other) colours. It may be useful to clarify that such 'overrides' go into the bottommost sections of the CSS block in options.

I seem to be seeing one bug though. Win7/SP1/x64 FF64. When closing the 'reader view' and going back to normal, it often returns me to the wrong page: not the one I was reading (normally and in reader), but the previous one. It's as if it was occasionally performing the "Go back one page" operation. This happens quite frequently, perhaps 30-50% of the time.

It would also be great if the original scroll position of the page could be preserved (the built-in version does this), but that's relatively minor.

Thank you!