I think the `.tailor-preview__viewport` element should use the [`spinner-2x.gif` that is already in core](https://github.com/WordPress/WordPress/blob/master/wp-includes/images/spinner-2x.gif). <img width="56" alt="screen shot 2016-09-11 at 12 25 25 am" src="https://cloud.githubusercontent.com/assets/522158/18415406/b4a4320e-77b6-11e6-9f77-2f4bfa579fa5.png">