JavaFX で透明なシーンを作成する

// Importing necessary packages.

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.layout.VBox;
import javafx.scene.text.Font;
import javafx.scene.text.Text;
import javafx.stage.Stage;
import javafx.stage.StageStyle;

public class FXTransparent extends Application {
  public void start(Stage PrimaryStage) {
    PrimaryStage.initStyle(
        StageStyle.TRANSPARENT); // Set the initial style to the stage to transparent
    Text txt = new Text("I'm totally \n transparent..."); // Creating a text element.
    txt.setFont(new Font(30)); // Set the font size to 30 for the text.
    VBox vbox = new VBox(); // Create a Vbox
    vbox.getChildren().add(txt); // Add the text to the Vbox
    Scene scene = new Scene(vbox, 400, 250); // Create a scene with Vbox and dimension
    scene.setFill(null); // Set the scene to no fill
    PrimaryStage.setScene(scene); // Add the scene to stage
    PrimaryStage.show(); // Visualize the stage
  }

  public static void main(String[] args) {
    launch(args); // Launch the application
  }
}

scene.getStylesheets().add("YourCSS.css")