If you don't use them, then it feels like a waste of screen space, I understand. Sadly, I have no idea how to solve that for you.
My observation is that while having many files open, the file Tab pushes the Layout tabs to the right. Is this not working for you?
However, the best and most direct way to give Maxon your idea of how it should work is via "Share Your Idea".
https://www.maxon.net/en/support-center
Thank you for the time to create your input.
If I have a chance to support your idea during a meeting, I will do that.
For colors, main Menu> Edit> Preferences> Interface Colors.
There is not a single color for only the Command Manager, that is Interface> General Background, and background 2 Inactive, as well Focus, or Select or as I saw it, you found the font color.
(I have no list here, and I have to search this as everyone else.)