Critical CSS for deferred styles while page is loading

critical-css.html

<style id="critical-css">
  /* Your styles here */
</style>
<script>
  const criticalStyleTag = document.getElementById('critical-css');
  document.addEventListener('DOMContentLoaded', function() {
    setTimeout(function(){
      criticalStyleTag.parentNode.removeChild(criticalStyleTag);
    }, 2000);
  });
</script>