Always rectangle

AlwaysRectangle.java

package Junit;

import javafx.application.*;
import javafx.scene.*;
import javafx.scene.layout.*;
import javafx.scene.paint.*;
import javafx.scene.shape.*;
import javafx.stage.*;

public class AlwaysRectangle extends Application {
    public static void main(String[] args) {
        launch(args);
    }

    @Override
    public void start(Stage primaryStage) throws Exception {
        Rectangle rectangle = new Rectangle(500, 250);
        rectangle.setFill(Color.TRANSPARENT);
        rectangle.setStroke(Color.BLACK);
        rectangle.widthProperty().bind(primaryStage.widthProperty().subtract(100));
        rectangle.heightProperty().bind(rectangle.widthProperty().divide(2));

        StackPane stackPane = new StackPane();
        stackPane.getChildren().addAll(rectangle);

        Scene scene = new Scene(stackPane);
        primaryStage.setScene(scene);
        primaryStage.show();
    }
}