This is something I've wanted for a long while.
It's currently white - you can't see chat or the list of people in the server you are in currently, which could be useful in case someone is trying to get ahold of you in chat while you are browsing servers to join, and could also be useful to evade the situation where you've been sitting in a quick aikido lobby for 40 minutes and someone joins RIGHT as you open the menu, and find a different server.

Small change, just a simple quality of life situation. There's no real debate to have here, it's a matter of preference really, so it could be optional. I'm sure there might be a file somewhere in the game folder where you can edit the texture, I'll have a look, but that's relatively "hacky".