Merge pull request #154 from mrwillis21/rubberBand

Add “rubber band” animation.

.animate-config.json

@@ -4,6 +4,7 @@
     "bounce": true,
     "flash": true,
     "pulse": true,
+    "rubberBand": true,
     "shake": true,
     "swing": true,
     "tada": true,

source/attention_seekers/rubberBand.css

@@ -0,0 +1,11 @@
+@keyframes rubberBand {
+	0% { transform: scale(1); }
+	30% { transform: scaleX(1.25) scaleY(0.75); }
+	40% { transform: scaleX(0.75) scaleY(1.25); }
+	60% { transform: scaleX(1.15) scaleY(0.85); }
+	100% { transform: scale(1); }
+}
+
+.rubberBand {
+	animation-name: rubberBand;
+}