Doesn't work on iOS inside an iframe

[lonekorean]

The background scrolls statically with the page. No physics-based movement.

The problem stems from how iOS handles iframe height: https://blog.codepen.io/2017/12/01/stupid-iframes-stupid-ios/ . This causes the canvas element to be sized to the content height instead of the viewport height.

Possible workaround is to hide the body, get viewport height, then restore body.