small confirmation dialog

js/index.js

@@ -123,12 +123,16 @@
         routingToolbar = L.easyButton(
             'glyphicon-trash',
             function () {
-                bootbox.confirm("Delete route?", function(result) {
+                bootbox.confirm({
+                    size: 'small',
+                    message: "Delete route?",
+                    callback: function(result) {
                         if (result) {
                             routing.clear();
                             onUpdate();
                             permalink._update_routing();
                         }
+                    }
                 });
             },
             'Clear route',