Hi epomatti, the empty frame that the web content goes into normally has a white background. Traditionally, you would create a userChrome.css file to apply a custom background color. It sounds as though Firefox's Dark theme doesn't do that yet, and it still needs to be done the old-fashioned way.

There is a project called ShadowFox that includes this and numerous other style rules to dark theme as much of Firefox as possible: https://overdodactyl.github.io/ShadowFox/

If you don't want to use all of that, just the one change, I could figure out which rule it is, or you could check the following subreddit where the question comes up from time to time: https://www.reddit.com/r/FirefoxCSS/

Hi Jscher

I installed it but there still is a small gap where (I assume) the page CSS is not loaded yet, and the background of the page is white for a short second.

Can that be changed as well?

Could I suggest asking about the problem on the Github site? Giving specific page examples for comparison might help.

https://github.com/overdodactyl/ShadowFox/issues

Try to add code to the userContent.css file.

• http://kb.mozillazine.org/userContent.css

/* about:blank */
@-moz-document url(about:blank){html,body{background-color:#ddd!important}}

• https://www.userchrome.org/what-is-userchrome-css.html
• https://www.userchrome.org/how-create-userchrome-css.html

cor-el said

Try to add code to the userContent.css file.

• http://kb.mozillazine.org/userContent.css

---

/* about:blank */
@-moz-document url(about:blank){html,body{background-color:#ddd!important}}

• https://www.userchrome.org/what-is-userchrome-css.html
• https://www.userchrome.org/how-create-userchrome-css.html

It didn't work.