Add lang-specific class

source/javascripts/app/_lang.js

@@ -29,8 +29,10 @@ under the License.
     $(".lang-selector a[data-language-name='" + language + "']").addClass('active');
     for (var i=0; i < languages.length; i++) {
       $(".highlight." + languages[i]).hide();
+      $(".lang-specific." + languages[i]).hide();
     }
     $(".highlight." + language).show();
+    $(".lang-specific." + language).show();
 
     global.toc.calculateHeights();