How can I load external CSS files like bootstrap.css and other external stylesheets to an html file having AMP? I checked AMP documentation. but didn't got a solution. I have to do SEO for a PHP static site and I am new to AMP and SEO.
AMP requires inline CSS for performance reasons.
https://amp.dev/about/how-amp-works/
https://amp.dev/documentation/guides-and-tutorials/develop/style_and_layout/style_pages/