I think we need to lower the Capitol building along with the stone it’s floating on, partially submerging the Capitol’s stone (gray) into the stone covered with grass. We can cover the irregularities and roughness at the border with vegetation and an effect like a cloud, for example.

Added 2 minutes later
And in general, all the stones should be the same color (that is, either sandy or gray, or if we leave them different colors, they should complement each other harmoniously).