OK, thanks Nikita, I have a Note 2 so that's a fairly big screen, but not as big as a tablet. I'll make sure I send it out to a few people with different screens for testing.

Brilliant.Thank you!!
Would you suggest I upload an image to fit the maximum screen size? Or would this make the app an unnecessarily large file size on smaller phones?

I'm just getting started, but the help has very little information about images. I added an image to my start screen of the right size to fit, but inevitably when I preview the page at different screen sizes the image doesn't fit any more. Is there a way of making the image resize dynamically? Thanks.