Themes now override page backgrounds.

[DMSledge]

If this is a case of user error, my apologies. I've noticed that when I use a theme, that theme background overrides the backgrounds of some pages. This can make pages with text that matches the theme unreadable.
Dark Reader extensions override this issue.

[U-alb]

Set browser.tabs.allow_transparent_browser to false in about:config

[guilhermeoliveiradecarvalho]

EDIT: I can confirm that Firefox 129.0.2 isn't affected; so this is not an upstream issue.

Confirmed here on 129.0.2, Fedora 34. Solution by @U-alb works perfectly, but needs an app restart to stick.

Firefox 135.0.1 doesn't suffer from this issue, as browser.tabs.allow_transparent_browser is false by default. Will check 129.0.2 to see if something changed along the way.

[leamocek]

Thanks for the solution! I've been looking for it for a long time!

[soda-caustica]

Many thanks for the solution!