JavaFX - 如何添加边框样式到HBox

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.layout.HBox;
import javafx.scene.paint.Color;
import javafx.scene.shape.LineTo;
import javafx.scene.shape.MoveTo;
import javafx.scene.shape.Path;
import javafx.scene.shape.SVGPath;
import javafx.stage.Stage;

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

  @Override
  public void start(Stage stage) {
    Path pathTriangle = new Path(new MoveTo(50, 0), new LineTo(0, 50),
        new LineTo(100, 50), new LineTo(50, 0));

    pathTriangle.setFill(Color.LIGHTGRAY);
    pathTriangle.setStroke(Color.BLACK);

    SVGPath svgTriangle = new SVGPath();
    svgTriangle.setContent("M50, 0 L10, 20 L100, 50 Z");
    svgTriangle.setFill(Color.LIGHTGRAY);
    svgTriangle.setStroke(Color.BLACK);

    HBox root = new HBox(pathTriangle, svgTriangle);
    root.setSpacing(10);
    root.setStyle("-fx-padding: 10;" + "-fx-border-style: solid inside;"
        + "-fx-border-width: 2;" + "-fx-border-insets: 5;"
        + "-fx-border-radius: 5;" + "-fx-border-color: blue;");

    Scene scene = new Scene(root);
    stage.setScene(scene);
    stage.setTitle("2D Shapes using Path and SVGPath Classes");
    stage.show();
  }
}