Frank Goossens on "[Plugin: Autoptimize] Above the fold CSS"

Evening Harry;
The easy solution (and, provided your CSS is not too big, quite performant) would clearly be to inline all CSS.

The more complex approach would require some code (using the autoptimize_filter_css_defer_inline filter from AO's API) to set the "above the fold CSS" depending on the useragent (as you did to not exclude jquery.js for mobile UA's). As you already have that previous experience, you could maybe have a go at that? :-)

have fun!
frank