I would say I think it looks great as it is, but it would also be delightful with sashing like the border around the center block. Oops just realized that's your floor! Anyway it appears to have been designed to have at least a border around the center block. I personally would probably add a narrow sashing between the blocks. Not sure how wide that would make the border around the center have to be. Might just have to play around with it to see what you like.