I think I've categorized the weirdness in the demo. The apparent dimensions and the working dimensions of the platforms don't seem to match. On the "upscreen" side, they're perfect. On the "downscreen" side, they're maybe one or two NG-thicknesses too long. As a result, NG appears to be floating in mid-air. It's particularly noticeable on the taller platform.
Good job, though, Kai. It's a great starting point.