Inline and Defer CSS?

“Inline and Defer CSS” seem such a great option, but there are 2 problems with it.

1. https://jonassebastianohlsson.com/criticalpathcssgenerator/ does not work! Or at least in my case it crashes when I paste my css in the textarea. The page freeze and I can’t do anything. So I wonder if there is an alternative for this problem, any other way to generate my above the fold css.

2. I’ve watched the video https://www.youtube.com/watch?v=k56E_7SFQoE (How to Eliminate Render Blocking CSS in Above-the-Fold Content in WordPress) and at the end of the video the guy discusses about an issue (different styles on different pages). And he talks about a next video to solve that problem, but the thing is the next video did not appear.

https://wordpress.org/plugins/autoptimize/