Remove restriction on units

[JacobDB]

I like to use em units so that I can scale different sections of a page as needed. This plugin seems fantastic, but it won't allow me to use em units, instead requiring rem or px. I don't understand this requirement; when I use clamp(3em, 1.5em + 3.125vw, 4em) manually, I get the same result. Is there a reason you're artificially restricting this?