It's mostly already available, just not the default: https://blog.thunderbird.net/2023/08/make-thunderbird-yours-how-to-get-the-thunderbird-115-supernova-look/

It's mostly already available, just not the default: https://blog.thunderbird.net/2023/08/make-thunderbird-yours-how-to-get-the-thunderbird-115-supernova-look/ https://blog.thunderbird.net/2023/08/make-thunderbird-yours-... I followed the steps in that blog post and was able to mostly get there. I have a bit less padding between folders than the mock-up showed (which seems like a theme thing rather than a configuration item), and I don't have profile pictures in the message list.