<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootswatch/3.3.7/flatly/bootstrap.min.css" integrity="sha384-+ENW/yibaokMnme+vBLnHMphUYxHs34h9lpdbSLuAwGkOKFRl4C34WkjazBtb7eT" crossorigin="anonymous" />
<link rel="stylesheet" href="//maxcdn.bootstrapcdn.com/font-awesome/4.6.3/css/font-awesome.min.css" integrity="sha256-AIodEDkC8V/bHBkfyxzolUMw57jeQ9CauwhVW6YJ9CA=" crossorigin="anonymous" />
<%=
    stylesheet_link_tag "site",
                        { type: nil, rel: "prefetch" }
%>
<%=
    stylesheet_link_tag "site"
%>

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootswatch/3.3.7/flatly/bootstrap.min.css" integrity="sha384-+ENW/yibaokMnme+vBLnHMphUYxHs34h9lpdbSLuAwGkOKFRl4C34WkjazBtb7eT" crossorigin="anonymous" />
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/font-awesome/4.6.3/css/font-awesome.min.css" integrity="sha256-AIodEDkC8V/bHBkfyxzolUMw57jeQ9CauwhVW6YJ9CA=" crossorigin="anonymous" />
<%=
    stylesheet_link_tag "site"
%>

Remove the prefetch tags for CSS
Remove the prefetch tags for CSS

Remove prefetch links for the CSS files as it seems to cause the files
to be fetched twice.
Also always serve the Font Awesome CSS over HTTPS.
