cant modify browser default background color - about:blank, about:newtab

cant modify browser default background color - about:blank, about:newtab, about:config. nothing. Stuck with glaring white screen every time I watn to open a tab in tor browser. This needs to be resolved. I contacted firefox about this too. apparently this file userContent.css in the chrome folder under tor browser root profile folder, doesnt do anything. It works in latest firefox on windows 10, it doesnt eliminate white flash when loading a page, but at least newtab is dark when I open a new tab in FF. This issue isnt specific to me. its GLOBAL. If someone can find a solution would be appreciated.

@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"); @-moz-document url("about:newtab"), url("about:blank") { body {background-color: #000000 !important;} }

@-moz-document url(chrome://browser/content/browser.xul) { browser[type="content-primary"] {background-color: #000000 !important} }

Trac:
Username: kingfitz