@Override
    public void start(Stage stage) throws Exception {
        AnchorPane root = (AnchorPane)FXMLLoader.load(getClass().getResource("main.fxml"));
        Scene scene = new Scene(root);
        scene.getStylesheets().add(getClass().getResource("main.css").toExternalForm());
        stage.setTitle("Calculator");
        stage.setOnCloseRequest(x -> {
            Platform.exit();
        });

        stage.setScene(scene);
        stage.show();
    }