OK, I just spent way too long on something unimportant (again):

I bring to you: smooth linear clamp() scaling, but with increasing something as you decrease the screen width!

From 1rem to 3rem: clamp(1, -0.5rem + 6.67vw, 3rem)

«Backwards» (video): calc(clamp(-3rem, -4.5rem + 6.67vw, -1rem) * -1);