Our email templates are rendered by a variety of email clients (Outlook, Gmail, Mac Mail) on a wide range of devices. Our standard templates are designed to be as consistent as possible across email clients.
With that said, much of the rendering, text / font / image size etc., are controlled by the email client itself. So, we made our templates as reliable as possible while ensuring maximum deliverability; too much rich text, formatting, and other fancy-pants stuff can trigger spam filters. Pretty hard to get actionable feedback when the surveys never make it to your customers' inbox!