There is more to this
replies(1):
calc( 1em + (2 - 1) * ( (100vw - 20em) / ( 100 - 20) ))
Works on mobile (and probably on a vertically oriented monitor) but it's pretty poor on a small and wide laptop screen. Fortunately it's constrained to 2em above a vw of 100em or ultrawide would be very interesting indeed.if you ctrl-minus a bit, it becomes more bearable