I needed to investigate inline CSS and went down the rabbit trail and am now silently screaming.
Things change so quickly, how does anyone stay on top of this stuff!
Google is teaching me...are there other resources?
If the external CSS resources are small, you can insert those directly into the HTML document, which is called inlining. Inlining small CSS in this way allows the browser to proceed with rendering the page. Keep in mind if the CSS file is large, completely inlining the CSS may cause PageSpeed Insights to warn that the above-the-fold portion of your page is too large via Prioritize Visible Content. In the case of a large CSS file, you will need to identify and inline the CSS necessary for rendering the above-the-fold content and defer loading the remaining styles until after the above-the-fold content.