Change newtab page background color to black.

#newtab-scrollbox{background-color:#000000!important;}
#newtab-window{background-color:#000000!important;}

I'm having trouble changing the background color of my newtab page to something other than the white that it is now. Browsing in a dark room is extremely blinding when opening the newtab page. In the past, I've modified my userContent.css file with the following (among other things): @-moz-document url("about:newtab") { #newtab-scrollbox{background-color:#000000!important;} #newtab-window{background-color:#000000!important;} } This has always worked and has achieved the results I want, but since I updated to Firefox 42.0 this morning it does not appear to work anymore. My newtab background color is off-white and is way too bright for my taste. I have a strong preference NOT to install any add-ons to do this as it should be easy to do from the userContent.css file. Not sure why my code no longer works... If I throw the following into userContent.css, *{background-color:#000000;}, it has the obvious effect of setting everything to black, including the background of the newtab cells. This tells me I can set the background, I just need the proper syntax. OS: Windows 8.1 Firefox Version: 42.0 Thanks!