You can edit your theme / plugin file, then wrap the CSS url in deferstyle() function like this:
Before:
<link rel=’stylesheet’ id=’fontawesome-css’ href=’/wp-content/themes/Techfind/assets/font-awesome/font-awesome.css’ type=’text/css’ />
After:
<script type=”text/javascript”>
deferstyle(‘/wp-content/themes/Techfind/assets/font-awesome/font-awesome.css’);
</script>
Note: There is no meaning to defer inline CSS.
With other Javascript files, you may want to see how to use the defer.js library on its official page:
https://github.com/shinsenter/defer.js
