@charset isn't being stripped from CSS; causes AMP validation error

[douglyuckling]

My theme's style.css begins with @charset "UTF-8";, but that apparently isn't allowed in AMP. It's not being stripped out when I use my theme in "paired mode", which causes an AMP validation error for me.

In case it matters, the version of this plugin I'm using is commit 5ba9f5b from the 0.7 branch.

[westonruter]

@douglyuckling thanks. This is something that is being addressed with having an actual CSS parser in #1048 now merged into develop (1.0-alpha). You can see from the unit tests that @charset is specifically being accounted for and getting stripped:

https://github.com/Automattic/amp-wp/blob/40d1945778c9917ed258e74595d504ad31719d39/tests/test-amp-style-sanitizer.php#L133-L140

Please try the develop branch and you should see it gets removed successfully.