Sara Soueidan on Twitter: "I’ve gotten some constructive, highly appreciated a11y feedback from my blog readers about using vw for font sizes. Basically, don’t.

If you’re using vw or other viewport units for element sizing, always bear in mind that viewport-unit sized elements are not user-zoomable. You can try on your own with this demo. An alternative could be to use calc(1em + 0.25vw) or similar calculations that don’t entirely depend on viewport units and therefore are scalable.