Solved Thunderbird: CSS Customization, Vol. 3 ??

I am using Thunderbird beta V149.0b1 ...
I use chrome/userChrome.css to set colors for the file and folder lists in TBird, but after a recent update, that code stopped working.
So I found a thread here from 2024, where a user named @das10 gave some excellent examples of how to properly use that file for setting colors, fonts, and more within Thunderbird... that is working *beautifully* for me... but one element is not getting background color set; this is visible in the attached image.

Note that when the messages listed in the Messages pane (actually called the Threads pane), do not fill the window, we get a blank space on the bottom that does not pick up the background color for that window.

Does @das10 or anyone else, know how to set the background for that open space???

@Gorlash; Welcome to Elevenforum.
I will take a look at this when I have time tomorrow.

Try to see if adding this css code helps to cover up that area:
userChrome.css

eg: Thunderbird v149.0 beta1

das10 said:

Try to see if adding this css code helps to cover up that area:
userChrome.css

Code:

#threadPane  .tree-view-scrollable-container {
  background-color: #A99B92 !important;
}

Click to expand...

YESSSSS!!!!!!!!!!!!!!!!! Thank you so much, @das10 !! You are the Master....

BTW, I'm curious about these field names;
What is the difference between #threadPane and #threadTree ??

I see the threadPane as generally the whole pane containing messages (typically the top right hand section in Tbird classic & wide view) and the threadTree as generally the area where you would find the list of messages.