This is not a bug report, just a request but i didnt know were to put it so i do it here, i hope it doesnt bother you a lot.

So actually when i try to change color of raid frame background it doesnt show me any alpha setting, just coloring to any color i want.
What i mean is that i wanted to have them black but a little bit transparent on the background.

Im not sure if there's an option but i cant find it. Any advices would be appretiated. I add a picture to explain myself better.

[https://imgur.com/a/BdL6mmL]

So if yo see its a deep black and i want it black but with a little bit less alpha. Any ideas ?