elector("#unity-progress-bar-full");
      const fullscreenButton = document.querySelector("#unity-fullscreen-button");
      const spinner = document.querySelector('.spinner');

      const canFullscreen = (function() {
        for (const key of [
            'exitFullscreen',
            'webkitExitFullscreen',
            'webkitCancelFullScreen',
            'mozCancelFullScreen',
            'msExitFullscreen',
          ]) {
          if (key in document) {
            return true;
          }
       