So you are saying, Thunderbird's stock dark theme isn't working in address book? With which version?

Correct. I do not have any third party themes. I tried some but none affected or helped with the issue.

When I use the light theme I can read them but there is no depth to the UI. Practically everything is white except the text which is a dark grey.

If this is not normal, how would I try to reset the themes?

I usually leave all these on "System Theme - Auto" but have been trying to resolve.

1. Please do Help > Troubleshoot Mode. 2. Do you see the problem? 3. Change the theme? 4. Do you see the problem?

Yes, The problem is still there.

I did a few times with the option to disable all plugins and with resetting all menus too. In all cases the White on White in the Address book remains.

Yes, The problem is still there. I did a few times with the option to disable all plugins and with resetting all menus too. In all cases the White on White in the Address book remains.

Please post a screen shot. Also....

With which Thunderbird themes? What settings do you have in Windows for Personalization > Themes and Personalization > Colors?

I created a new address book so as not to expose personal data. Here is a screen shoot of what I see. One is a user not selected and another with selected.

As for themes on Windows 11. That is the current OS. It is a new build. It is on a custom theme. I eveidently changed something. Most likely the background image. Don't usually change much and keep the OS simple on this system.

I can try changing up the theme and see if that affects it. Before I do that is there a way to see the CSS in the address book to see what element is being used to describe what is being displayed?

Tools > Developer Tools > Inspector

Given that this doesn't go away in Thunderbird's Troubleshoot Mode, I have to think some setting in Windows is affecting you, in appearance or accessibility.

I did test changing up the themes and all dark themes break your UI.

I think this is a bug in Thunderbird. I think this because no other app on my system has this issue. I think what is happening is that the second column is staying on white when it should go dark. The first column also is an issue as it goes dark but does not turn text white or a lighter shade with a dark theme is applied.

This all tells me that the UI in the Address book is not the same as the UI elements in the email app of Thunderbird. The fix would be to use the same elements in the address book as are in the email app portion. The titles or CSS element names should be changed to match those of the email client which works fine in all themes. Something is not changing in the address for the labels of the elements correctly.

I also discovered. If I set windows to a light theme address book is legible BUT if I then change Thunderbird to a dark theme, I end up with the same issue in the address book. It goes white on white again.

This makes me think the labels are definitely incorrectly assigned in the address book.

Perhaps have a look at the windows colours. as shown in the image. I found changing the default app mode had quite an impact on how Thunderbird displayed content using it's own themes.

Yes, that seemed to help your app. But then all the other apps on the system do not work. Some have a theme option to change to dark but most do not. Thus, I lose the ability to control dark mode by the system correctly and now I have to manage all apps and their appearance vs. just use the system mode.