Thunderbird has a black background color. [Linux.]

[Jan_B]

My Thunderbird has all of a sudden a black background except for the reading pane. In messages the header is black and the text body has the normal white background (both in received e-mails as well as new e-mails). The text colour changed to white, so everything is still legible, but I prefer the normal white background.

I have not installed anything (e.g. a black theme) nor did I change something in the program.

I am running 68.7.0 (64-bit) on a Ubuntu 16.04 machine.

Does anyone know how I can get the white background back?

[tanstaafl]

Check if it somehow switched to the dark theme that is built into Thunderbird.

See if the problem goes away using safe mode (help -> restart with add-ons disabled). If it does then either a theme, extension or a .css file in the optional chrome directory in your profile is to blame.

[Jan_B]

"Check if it somehow switched to the dark theme that is built into Thunderbird. " -> Where can I find this option? (I checked under preferences, but did not see it there)

"See if the problem goes away using safe mode" -> I did that, but the problem persists

[tanstaafl]

tools -> options -> add-ons -> themes under Windows. I believe that would be edit -> preferences -> add-ons -> themes under Linux

[WaltS48]

Nope it is Tools > Add-ons > Themes from the Menu bar or Menu button > Add-ons > Themes.

[Jan_B]

Okay I found it. The selected option was "Default". So it was not inadvertently set to "Dark". Now I selected "Light", which is better though slightly different from the original setting.

I noticed it says that the default setting uses the operating system colour scheme. So the cause may lie in Ubuntu rather than Thunderbird.