// Invoke setBodyClass() when a key is pressed.
    document.keyup(function(event) {
      switch (String.fromCharCode(event.keyCode)) {
        case 'D':
          setBodyClass('default');
          break;
        case 'N':
          setBodyClass('narrow');
          break;
        case 'L':
          setBodyClass('large');
          break;
      }
    });
  });