I am optimizing a website load, and find the (usual, I suppose) message from Google's PageSpeed Insights 'remove blocking CSS from top of your website'.
I am in doubt because:
You can split your CSS into two parts. The first one contains the code to render the content
"above the fold". This is what you see without scrolling. The rest can be included at the bottom of your page.
Your Browser only get the important code to render in order to provide the user as soon as possible a seemingly rendered page, while the browser renders the bottom of the page "in background".
But in my tests, it does not have as great an impact on the page-speed.