I was a bit unhappy with the default theme of Zorin OS. I found the light theme too bright and the dark theme too dark. Then I remembered that the old Windows allowed me to set any color I wanted for the title bar and so on in GUI.
I don't remember an option for that on gnome, but I remember seeing it when I tried out LXQT. I'm guessing xfce should have it as well but can't say for sure.