hettlage (136) [Avatar] Offline
If you use the CSS from listing 2.19

:root {
  font-size: calc(0.5em + 1vw);

Safari (10.0.2) doesn't update the font size when you change the viewport size. Maybe it might be worth pointing this out in the discussion of calc()?
Keith J Grant (36) [Avatar] Offline
Interesting. I know older versions had issues, but 10.x is surprising. Does it update if you refresh the page after resizing?
hettlage (136) [Avatar] Offline
Yes, the font size is updated if you reload the page after resizing the browser.
428149 (29) [Avatar] Offline
Calc() should never be used without a polyfill. Over 16% of browsers in the wild don't support it.