reworked single post view

_includes/navigation.html

@@ -1,6 +1,6 @@
 <!-- Nav Menu Section -->
    <div class="logo-menu">
-    <nav class="navbar navbar-default navbar-fixed-top" role="navigation" data-spy="affix" data-offset-top="50">
+    <nav class="navbar navbar-default navbar-fixed-top affix" role="navigation" {% if page.section-type == "index" %} data-spy="affix" {% endif %} data-offset-top="50">
       <div class="container">
         <!-- Brand and toggle get grouped for better mobile display -->
         <div class="navbar-header col-md-3">