All my terminals applies a glowing outline... I patched Kitty [1] with a shader to apply it (Kitty already uses shaders for the terminal rendering). I should clean it up and put it up somewhere. I did it partly because I like the look, partly because it gives me much more flexibility in having partially translucent terminal windows without making the text unreadable.
First time I am hearing of kitty. As a heavy tmux user who has had to yak shave a few times due to 256 color support issues, I'm going to check this out!
If you use gpakosz tmux config you may find the following set up useful. https://github.com/lukesmurray/bootstrap/tree/master/.config... I replicated most of the key bindings so you can use splits without tmux. Still no support for multiple sessions or persistence but that’s on kittys roadmap
Something similar, but perhaps even more 'plain' – https://kvak.io