code: private void manageDefaultStyleSheet(final Scene scene) {
          if (scene.getStylesheets().isEmpty()) {
              // No style sheet has been added to the scene
              LOGGER.log(NO_CSS_DEFINED);
              addCSS(scene, JRebirthStyles.DEFAULT);
          }
  
      }
docs: Attach default CSS file if none have been previously attached.
  
  @param scene the scene to check