This could be a one-word article: don’t.
More specifically, don’t design websites for any specific device. That way lies pain (and it is not the way of the web).
But read on for a textbook example of how not to introduce new CSS properties. Apple proposed the new syntax that they’re shipping. Now it’s getting standardised …with a different name. So basically Apple are shipping the equivalent of a vendor-prefixed property without the vendor prefix.