Once the stylesheet has finished downloading the
media attribute must be set to a valid value so the style rules will be applied to the document. The
onload event is used to switch the
media property to
This method of loading CSS will deliver useable content to visitors much quicker than the standard approach. Critical CSS can still be served with the usual blocking approach (or you can inline it for ultimate performance) and non-critical styles can be progressively downloaded and applied later in the parsing / rendering process.
<link> elements in a