Very cute! I like the small detail, that your finish position becomes your new starting position, and the next level plays around it.
Not sure if it needs any additional mechanics. But if you were thinking about some — try teleports! So the player has to memorize several tracks connected by them.
I would probably make intro skipable — it's a bit irritating if you refresh the page or come back to play later.
I'm not sure about screen resolution. But try changing Embed options in your itch.io game settings.