Thanks Greg , for such a fast reply.
But as far as I know i am using html5, since my doc starts with <!DOCTYPE html>
Also I forgot to mention following error :
Element link is missing required attribute property.
<link rel='stylesheet' id='sow-social-media-buttons-wire-13024ebeef13-css' href='{MY_SITE_URL}/siteorigin-widgets/sow-social-media-buttons-wire-13024ebeef13.css?ver=4.3.1' type='text/css' media='all' />
