[SplitMenuButton] : css style to change background not visible.

 @Override
    public void start(Stage stage) throws Exception {
        BorderPane root = new BorderPane();
        
        SplitMenuButton splitButton = new SplitMenuButton();
        splitButton.setText("SplitButton");
        Button button = new Button("Button");
        String style = "-fx-background-color:red;";
        splitButton.setStyle(style);
        button.setStyle(style);
        
        root.setCenter(HBoxBuilder.create().children(splitButton, button).spacing(50).build());
        
        Scene scene = new Scene(root, 300, 100);
        stage.setScene(scene);
        stage.setTitle(VersionInfo.getRuntimeVersion());
        stage.show();
    }