Ability to specify dial size in rem units or even em

[pg1671]

It would be useful to be able to specify the size of the dial this way.

I need to be able to responsive change the size of the dial .. how are others doing this?

I tried 100% inside a fixed size div that was rem sized and it worked on the desktop browser but the iphone drew the dial outside the bounds (probably something to do with high dpi display I think causing the dimensions to double on the canvas).