The resources CSS and JS appear as "http://" without the HTTPS plugin.
<script type='text/javascript' src='http://paperpile.com/blog/wp-content/themes/paperpile-blog/js/modernizr.js?ver=2.8.1'></script>
The other links seem to be ok with "https" even without the plugin.
<a href="https://paperpile.com/blog/2014/07/10/improved-google-docs-citations/">