I think your stairs, and your maps overall, look very good. Even earlier versions I could tell what was going up or down.

If I was going to nitpick the only thing I would say is maybe the stair shadows could be slightly transparent (not solid black) and the edge of the shadow on the stairs going down (like the part just to the right of the horizontal red arrow tip on the last update of the two stairwells) could be less hard, more feathered.

But that is very minor and I'm not familiar with VTT so my comments may be moot.

Great job so far on these maps.