fix panel region vbox styling

Author: tschie

src/main/resources/css/style.css

@@ -1,4 +1,4 @@
-.panel-region {
+VBox.panel-region {
   -fx-background-color: rgba(0,0,0, 0.3);
   -fx-padding: 10.0 10.0 10.0 10.0;
 }