Pixels work fine in real browsers, they worked fine even since and they don't require strange math or resetting a child element. And because they work, they don

Pixels work fine in real browsers, they worked fine even since and they don't require strange math or resetting a child element. And because they work, they don't require a fallback. If a specific browser doesn't support a very specific feature, I'd say: screw that browser. This isn't about an essential page feature missing, heck, it's not even about the page not looking the same across browsers. This is about allowing the user to change the look of the page. If a user is advanced enough to even know they can do that, then they might also be advanced enough not to use IE. This feels like optimizing the completely wrong thing - and even changing the spec to accomodate a browser issue (which will never support the new unit anyways). At this point, there's no advantage to use 1rem instead of 10px, aside of IE9 support.