That’s false. If that were the case, nobody could use new features unless all three major browser engines supported them at the same time and that’s clearly no

That’s false. If that were the case, nobody could use new features unless all three major browser engines supported them at the same time and that’s clearly not happening. It’s pretty easy to use @supports to check for feature support. CSS and HTML are pretty resilient with code they don’t understand. Remember Chrome ships things all the time other browsers don’t support but that’s okay for some reason…