Styling to make it clearer where the editor is

IPython/html/templates/texteditor.html

@@ -5,6 +5,11 b''
 {% block stylesheet %}
 <link rel="stylesheet" href="{{ static_url('components/codemirror/lib/codemirror.css') }}">
 <link rel="stylesheet" href="{{ static_url('components/codemirror/addon/dialog/dialog.css') }}">
+<style>
+#texteditor-container {
+    border-bottom: 1px solid #ccc;
+}
+</style>
 
 {{super()}}
 {% endblock %}
@@ -43,7 +48,7 b' data-file-path="{{file_path}}"'
 </div>
 </div>
 
-<div id="texteditor-container"></div>
+<div id="texteditor-container" class="container"></div>
 
 {% endblock %}