Fixing W3 Total Cache CDN with Beaver Builder CSS media

functions.php

<?php

// W3 Total Cache Integration with Beaver Builder
add_filter( 'fl_builder_render_css', __NAMESPACE__ . '\bb_plugin_cdn_url' );
function bb_plugin_cdn_url( $css ) {

  // Based on wp-content/plugins/w3-total-cache/extensions/WordPressSEO.php
  if ( class_exists( 'W3_Plugin_CdnCommon' ) ) {
    $site_url = wp_upload_dir();

    $w3_plugin_cdncommon = w3_instance( 'W3_Plugin_CdnCommon' );
    $cdn = $w3_plugin_cdncommon->get_cdn();

    // If we are using a cdn with w3tc
    if ( $cdn ) {
      $parsed = parse_url( $site_url['baseurl'] );
      $path = $parsed['path'];

      // Grab the CDN path
      $remote_path = $w3_plugin_cdncommon->uri_to_cdn_uri( $path );

      // Format the CDN url
      $new_url = $cdn->format_url( $remote_path );

    // If we are not using a cdn with w3tc
    } else {

      // Don't format the css
      return $css;
    }

    // Replace the uploads URLs with the new URL
    return str_replace( $site_url['baseurl'], $new_url, $css );
  }

  // Don't format the css
  return $css;
}