use the invaders game as 'loading screen'

pdb-js/src/assets/css/invaders.css

@@ -0,0 +1,30 @@
+.invader {
+	background: url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABoAAAAUCAYAAACTQC2+AAAAAXNSR0IArs4c6QAAAAZiS0dEAP8A/wD/oL2nkwAAAAlwSFlzAAALEwAACxMBAJqcGAAAAAd0SU1FB9kKGRAxBENShygAAAAZdEVYdENvbW1lbnQAQ3JlYXRlZCB3aXRoIEdJTVBXgQ4XAAAAbUlEQVRIx9WVQQrAMAgEM6X///L2FCihYvRg7F416LCsQdKo0DWKZA4CBGzjev1lRHgezS0lkan3IYr485ZFdo5oJZkbWoRWfSWrJ8p6suvZucsgCS8THsHX+zKiO5uLaO763bpobvoS/e6HfQBzIE0PhAsDxgAAAABJRU5ErkJggg==);
+	width: 26px;
+	height: 20px;
+}
+
+#invaders_area {
+	position:fixed;
+	display:none;
+	z-index: 9999;
+	cursor:crosshair;
+	background: url("../img/city_silhouette.png");
+	background-repeat: repeat-x;
+    background-position-y: bottom;
+}
+
+
+#invaders_game_over {
+	display: none;
+    justify-content: center;
+    align-items: center;
+    height: 100%;
+}
+.invader_notify {
+	border: solid 2px black;
+	padding: 1em;
+	background: #ccc;
+	z-index: 9999;
+	cursor:pointer;
+}