Great work. I’ve been working on Mimetic a JS lib for fluid fonts. I’m not biased to a CSS solution but my problem with calc solutions so far is that two set value have to be set for max and min, which seems like more added maintenance depending on the project it’s used with.
It would be great if your function could accept a single value (as a rem for e.g.) , and allow a max/ min widths that could be set once to affect all poly-fluid-sizing usage.