"Undulating" is the wrong word.
"Wobbles over the edge of next flight of stairs," a bit clunky. May need a determiner to distinguish which flight.
"And down/and down," remove "and" just "down/down" I think would hold better with the image.
Really nice. Thanks for sharing
Writing is an inside joke.
Its publication, an opportunity to let others in.
The same can be said of all art