Update app.component.css

Author: bmarkov

demos/tree/dropdownmode/src/app/app.component.css

@@ -2,6 +2,11 @@
 	 width: 300px;
   }
 
+.smart-tree-popup {
+	position: absolute;
+	border: none;
+}
+
 @media only screen and (max-width: 700px) {
   smart-tree {
 	 width: 100%;