Yep, have talked about this with Kate. Basically, we just want things to have the same proportions on each device.

Figuring out the actual physical screen size is tricky and doesn't work on all devices (`cm` doesn't correspond to actual centimeters on the screen). If/when we get that working, we'd just make the containing div (in this case, `#rectangle`) smaller; we'd still want the proportions to be the same.