如何更改ChoiceBox的默认大小？

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.ChoiceBox;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

public class ChoiceBoxExample extends Application {

    @Override
    public void start(Stage primaryStage) {
        ChoiceBox<String> choiceBox = new ChoiceBox<>();
        choiceBox.getItems().addAll("Option 1", "Option 2", "Option 3");
        choiceBox.setPrefWidth(200); // 设置宽度
        choiceBox.setPrefHeight(30); // 设置高度

        VBox root = new VBox(choiceBox);
        Scene scene = new Scene(root, 400, 300);
        primaryStage.setScene(scene);
        primaryStage.show();
    }

    public static void main(String[] args) {
        launch(args);
    }
}