Is there a non-hacky way to prevent pinch zoom on iOS 11.3 Safari?

While there isn't a non-hacky way to prevent pinchzoom, there is a hack that works on iOS 11.3 Safari still. At least for now. See inobounce that handles both rubber band behavior and pinchzoom in one fell sweep.

You can use touch-action: none on the html, body selector: https://developer.mozilla.org/en-US/docs/Web/CSS/touch-action#none

https://github.com/msand/InfiniDraw/commit/b96aac5f8313f56da7be6f9e9f24648ab02fc444