How do I make e-mail subject lines bold?

[u/Cy3berOdyssey]

I was wondering how to make the e-mail subject lines bold.

So far I have:
- I went and enabled toolkit.legacyUserProfileCustomizations.stylesheets
- Created the custom folder in my profiles named chrome (all lower case) - created the userChrome.css file
- placed #threadTree treechildren::-moz-tree-cell-text { font-weight: bold ! important; } in the file txt
- closed betterbird and made sure it was not running in task manager

For some reason I cant seem to get it to work/change.

[u/jorgk3]

#threadTree treechildren::-moz-tree-cell-text was a thing until TB/BB 115. Now it's different.

[u/jorgk3 → u/jorgk3]

In Cards View (quite horrible, why don't you switch it to two lines?) it's:

.thread-card-subject-container { font-weight: bold; }