I don't think we can control colors ourselves but I have not delved deeply into that (there's some intriguing little buttons across the top of the reply panel) , and of course changes in the buttons is a programming thing. There's a few different threads where people are suggesting improvements. If mgt agrees and it's easy, they tend to do it right away. If it's more complicated they may reply put it on the 'to-do' list. Alan seems to be the one that does that kind of stuff.
Right now it's just "big purple box at top" or "little purple box at bottom".