diff --git a/.gitignore b/.gitignore
index 28a83b48f..907ccb8cc 100644
--- a/.gitignore
+++ b/.gitignore
@@ -35,7 +35,7 @@ src
 .idea/
 Read the Docs
 config.rst
-
+*.iml
 /.project
 /.pydevproject
 
diff --git a/notebook/templates/page.html b/notebook/templates/page.html
index 9e68da1b2..8a7e789e0 100644
--- a/notebook/templates/page.html
+++ b/notebook/templates/page.html
@@ -122,7 +122,7 @@ dir="ltr">
   </div>
 </noscript>
 
-<div id="header">
+<div id="header" role="navigation" aria-label="Top Menu">
   <div id="header-container" class="container">
   <div id="ipython_notebook" class="nav navbar-brand"><a href="{{default_url}}
     {%- if logged_in and token -%}?token={{token}}{%- endif -%}" title='{% trans %}dashboard{% endtrans %}'>
@@ -153,11 +153,12 @@ dir="ltr">
 
   {% block header %}
   {% endblock %}
-</div>
+
+    </div>
 
 <div id="site">
-{% block site %}
-{% endblock %}
+    {% block site %}
+    {% endblock %}
 </div>
 
 {% block after_site %}
diff --git a/notebook/templates/tree.html b/notebook/templates/tree.html
index d84a973c1..113be4cc7 100644
--- a/notebook/templates/tree.html
+++ b/notebook/templates/tree.html
@@ -1,5 +1,4 @@
 {% extends "page.html" %}
-
 {% block title %}{{page_title}}{% endblock %}
 
 
@@ -27,7 +26,8 @@ data-server-root="{{server_root}}"
 {% block site %}
 
   <div id="ipython-main-app" class="container">
-    <div id="tab_content" class="tabbable">
+
+    <div id="tab_content" class="tabbable" role="main">
       <ul id="tabs" class="nav nav-tabs">
         <li class="active"><a href="#notebooks" data-toggle="tab">{% trans %}Files{% endtrans %}</a></li>
         <li><a href="#running" data-toggle="tab">{% trans %}Running{% endtrans %}</a></li>
@@ -204,4 +204,4 @@ data-server-root="{{server_root}}"
 
 
 <script src="{{ static_url("tree/js/main.min.js") }}" type="text/javascript" charset="utf-8"></script>
-{% endblock %}
+{% endblock %}
\ No newline at end of file