The pictures work perfectly
Nice a clean look (this suits my personal taste).
Just one minor point to consider for the future:
cobblestones have fine sand between them instead of large gaps.
Without sand to lock them down they would wobble all over the place. I don't have any tips/hints for how to achieve this, it depends on how the cobblestones are made. Maybe very fine sand and then locked with laquer.

One possible method that could possibly work:
Take ordinary sand based putty used for smoothing walls before covering with wall paper. Not the light weight stuff but the one based on very find sand.
Mix it with some pigment powder, water colours or water based paint to get a usable colour instead of bright white. Smear it on a board, let it dry, use a fine sand paper to grind it off again. This gives you a very fine coloured dust which contains the "glue" from the original wall putty.
Brush the dust into the cracks between the cobble "stones", moisten it when all the cracks have been filled, let dry.
Clean up the cobble stones if needed.
/ Robin