update: it is causing sites to crash or slow down (ebay) even if not turned on - so i have do deactivate it (tested with FF55 Win10-32bit)

could you please add a dark theme to the Firefox pages (blanc page, addon page, etc...) too?

some elements may disappear with dark mode on
works not on every page (addons.mozilla.org)??

overall it is a nice, small and easy to use addon. (i´m using the dark grey theme)