Sorry, I was commenting generally. Don’t know about AMP. How does that make sense, though? What performance reasons could there possibly be for inlining CSS that doesn’t apply to any element in a page?
Likewise, I'm sorry, I didn't mean "you have to inline CSS that doesn't apply".
However, if you have non-render blocking CSS, or CSS that's used for below the fold or generally lower down the page content, "only render critical CSS inline" is usually coupled with "and then have the rest of your CSS in an external stylesheet". Which you are not allowed to do.
