GP theme displaying differently on mobile than advertised

Hi there,

Very new to this but I recently bought GP Premium and set up using the 'Broadcast' template, part of the reason was for the element overlap with the header/banner on the home page. The site library showed this overlap on all devices. However I've set up the theme and the overlap only displays on desktop and tablet, on mobile the first element actually disappears under the header banner (I can see the bottom of it poking out).

I've not touched the code because I'm very clueless about it but just wondering why this has happened and how i can 'bring to front' the first blog post element that's hiding underneath the header. Hope that makes sense!

Thank you