discourse/app/views/common/_discourse_stylesheet.html.erb

<%- unless SiteCustomization.override_default_style(session[:preview_style]) %>

  <script type="text/javascript">
    (function() {
      var h = document.getElementsByTagName('html')[0];
      window.isMobileView = (localStorage && localStorage.mobileView) ? (localStorage.mobileView === 'true') :
          Modernizr.mq("only screen and (max-width: 480px), only screen and (max-device-width: 480px)");

      h.className += (isMobileView ? ' mobile-view' : ' desktop-view');
      if(isMobileView) {
        document.write(<%= stylesheet_links(:mobile).inspect.html_safe %>);
      } else {
        document.write(<%= stylesheet_links(:desktop).inspect.html_safe %>);
      }
    })();
  </script>

<%- end %>

<noscript>
  <%= stylesheet_link_tag "desktop" %>
</noscript>

<%- if staff? %>
  <%= stylesheet_link_tag "admin"%>
<%-end%>