I just wanted to say how much I appreciate this! I have an absolutely terrible time with color -- I have no sense for it. But I can use this -- this makes sense to me, I think because it's used to shade the circles. Thanks so very much! Please consider doing more of these!!!
It says in the comments they "often" mix with blue/yellow. Which means after the fact or for higher contrast they go back in to their chosen color palette and add blue's and yellows for shadows and highlights.