Bug 20622: Add some color to bootstrap modal headers and footers

Right now the bootstrap modal header, body and footer are all white. It would be nice to give them a bit of color.

Test Plan:
1) Apply this patch
2) Find a patron, click the 'add message' button
3) Note the modal header and footer now have a background color

Signed-off-by: Kyle M Hall <kyle@bywatetsolutions.com>

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>

koha-tmpl/intranet-tmpl/prog/css/staff-global.css

@@ -2690,6 +2690,15 @@ a.close:hover {
     margin-left: 0;
 }
 
+.modal-body {
+    background-color: #FFF;
+    overflow-y: auto;
+}
+
+.modal-content {
+    background-color : #EDF4F6;
+}
+
 /* Redefine a new style for Bootstrap's class "close" since we use that already */
 /* Use <a class="closebtn" href="#">&times;</a> */
 .alert .closebtn{position:relative;top:-2px;right:-21px;line-height:20px;}