Good question. This isn’t currently possible via the UI options. You can of course apply any CSS you want via the custom code editor, but if you generally work with the UI options that’s not an ideal workaround.
We do plan to add this option in future. I was expecting to get this request more often but yours is the first. Right now, we’re concentrating on improving the existing features. I’ll explain this further on my reply to your question about animations and transforms.