I use Spark Page for creating an online newsletter and primarily accomplish this on my desktop. On Adobe Spark Page, there is a preview button at the top of your creation that allows you to preview what your creation will look like on the desktop. It would be extremely useful if you would add a "Preview on Mobile" option so that they same design could be previewed. As it is, I must exit the application, sync and open it on a mobile device just to see how it is going to look on mobile. As most online users now are looking at items on a mobile device, this seems like a reasonable request for social media managers.