How to change UI colors for gitk?

That appears to be the headbgcolor, which is not available from the GUI colour settings.

Close gitk, then modify ~/.config/git/gitk and change

set headbgcolor green

to some other colour. Hex codes appear to be supported unquoted, e.g.

set headbgcolor #123456

git ubuntu gitk

For Windows, you need to change headbgcolor in your %HOMEPATH%\.gitkhidden file.

CodeHunter