code: private void manageStyleSheetReloading(final Scene scene) {
          if (CoreParameters.DEVELOPER_MODE.get() && scene != null) {
  
              for (final String styleSheet : scene.getStylesheets()) {
  
                  getFacade().serviceFacade().retrieve(StyleSheetTrackerService.class).listen(styleSheet, this.application.scene());
              }
              getFacade().serviceFacade().retrieve(StyleSheetTrackerService.class).start();
          }
      }
docs: Manage style sheet reloading by using a custom service provide by JRebirth Core.
  
  @param scene the scene to reload in case of Style Sheet update