That's a tough one!
I *LOVE* the dark framing. I think it's perfect.
The piano key? Normally I like how those turn out, but in this case the blocks are so stunning, they should be stand alone. Could you do a pinstripe solid color, say teal? Then it could be:
Dark Border
Teal Pinstripe (or other color)
Dark Boarder
Bind in the same dark color