add date in header of printed pages (#2359)

calebasse/agenda/templates/agenda/service-activity.html

@@ -10,6 +10,8 @@
 
 {% block agenda-content %}
 
+<div class="print-only page-header">{{ date|date:"DATE_FORMAT"|lower }}</div>
+
 <h2 class="print-only">Activité du {{ service_name }} - {{ date|date:"DATE_FORMAT"|title }}</h2>
 
 <table class="main" id="activity">

calebasse/static/css/print.css

@@ -77,3 +77,8 @@ div.summary {
 div#sidebar {
   display: none;
 }
+
+div.page-header {
+  position: fixed;
+  top: 0;
+}