Hello,

Please replace this code:

echo '<div class="widget-heading"><a href="#" class="close-side-widget wd-cross-button wd-with-text-left"></a></div>';

for this one:

echo '<div class="widget-heading"><div class="close-side-widget wd-action-btn wd-style-text wd-cross-icon"><a href="#" rel="noffollow">close</a></div></div>';

Best Regards