misc: display a warning to IE < 9 (#9024)

gadjo/static/css/gadjo.css

@@ -775,6 +775,16 @@ ul#sidepage-menu li a {
 	border-radius: 2px;
 }
 
+div.old-ie-warning {
+	background: #ffd800;
+	padding: 1em;
+}
+
+div.old-ie-warning p {
+	margin: 0;
+	line-height: 150%;
+}
+
 ul#sidepage-menu li a.icon-add { background-image: url(icons/add.small.png); }
 ul#sidepage-menu li a.icon-calendar { background-image: url(icons/calendar.small.png); }
 ul#sidepage-menu li a.icon-categories { background-image: url(icons/categories.small.png); }

gadjo/templates/gadjo/root.html

@@ -37,6 +37,20 @@
       <h1>{% block site-title %}{% endblock %}</h1>
       {% block subheader %}{% endblock %}
     </div>
+
+{% block old-ie-warning %}
+<!--[if lt IE 9]>
+<div class="old-ie-warning">
+  {% blocktrans %}
+  <p><strong>Do you know your web browser is obsolete?</strong>  We recommend
+  you to <a href="http://windows.microsoft.com/en-us/internet-explorer/download-ie">update
+  your web browser</a> or to <a href="http://browsehappy.com/">use
+  different web browsers</a> as some features may not work.
+  {% endblocktrans %}
+</div>
+<![endif]-->
+{% endblock %}
+
     <div id="main-content">
       <div id="more-user-links">
         {% block more-user-links %}