Okay, time for a design change. I checked I don't have enough of the tan/brown color for the borders, but I have enough of the dark blue. So my thought is to use the dark blue as borders with the tan/brown for the corners. Then I will use the piano keys and the blue squares for the back.
Thanks for your help.
Jen, thank you. You made this so picture friendly that I didn't have any trouble following along. Now just to do.