WordPress - Eliminate render-blocking resources

gistfile1.txt

function addRelPreloadTagToEnqueueStyles($html, $handle) {
  // Put to array all styles which you want to add tag rel="preload"
  $styles = ['app', 'wp-block-library', 'contact-form-7', 'cf7cf-style'];
  foreach ($styles as $singleStyle) {
    $html = preg_replace("/id='" . $singleStyle . "-css'/", " id='" . $singleStyle . "-css' rel='preload' as='style' ", $html);
  }
  return $html;
}
add_filter('style_loader_tag', 'addRelPreloadTagToEnqueueStyles');