I really love addons like 'Dark Background and Light Text', but they don't work with the 'New Tab', 'about:*' and addons.mozilla.org pages like most other addons in recent Firefox.

For the 'New Tab' page I now use 'New Tab Tools' to set the background to black. But I am still unhappy that its not possible to set all other pages to a dark theme.

Also that Vimium doesn't work with those pages is a shame as well. I hope Mozilla fixes that regression soon. Web Extensions should have the same abilities as the XUL extensions.