style fix menusystem

src/opnsense/mvc/app/views/layout_partials/base_menu_system.volt

 <aside id="navigation" class="page-side col-xs-12 col-sm-2 hidden-xs">
     <div class="row">
         <nav class="page-side-nav" role="navigation">
-            <div class="list-group" id="mainmenu">
+            <div id="mainmenu" class="panel">
                 {% for topMenuItem in menuSystem %}
-                <a href="#{{ topMenuItem.Id }}" class="list-group-item {% if topMenuItem.Selected %}  active-menu-title {% endif  %}" data-toggle="collapse" data-parent="#mainmenu"><span class="{{ topMenuItem.CssClass }} __iconspacer"></span>{{ topMenuItem.VisibleName }} </a>
-                <div class="collapse  {% if topMenuItem.Selected %} active-menu in {% endif  %}" id="{{ topMenuItem.Id }}">
-                    {% for subMenuItem in topMenuItem.Children %}
-                        {% if acl.isPageAccessible(session.get('Username'),subMenuItem.Url)  %}
-                            <a href="{{ subMenuItem.Url }}" class="list-group-item {% if subMenuItem.Selected %} active {% endif  %}">{{ subMenuItem.VisibleName }}</a>
-                        {% endif %}
-                    {% endfor %}
+                <div class="panel list-group">
+                    <a href="#{{ topMenuItem.Id }}" class="list-group-item {% if topMenuItem.Selected %}  active-menu-title {% endif  %}" data-toggle="collapse" data-parent="#mainmenu"><span class="{{ topMenuItem.CssClass }} __iconspacer"></span>{{ topMenuItem.VisibleName }} </a>
+                    <div class="collapse  {% if topMenuItem.Selected %} active-menu in {% endif  %}" id="{{ topMenuItem.Id }}">
+                        {% for subMenuItem in topMenuItem.Children %}
+                            {% if acl.isPageAccessible(session.get('Username'),subMenuItem.Url)  %}
+                                <a href="{{ subMenuItem.Url }}" class="list-group-item {% if subMenuItem.Selected %} active {% endif  %}">{{ subMenuItem.VisibleName }}</a>
+                            {% endif %}
+                        {% endfor %}
+                    </div>
                 </div>
                 {% endfor %}
             </div>