Safari has the responsive design mode which is a great help, but it is not always so easy in sparkle to understand exactly which screen size you are editing for.
I made a simple template that helps to better see which device / device orientation you are editing for and thought that some of the community might find it useful.
All you would have to do would be to copy the group into your document (or if you can’t see layers, to copy and paste the text elements themselves which might of might not work). Then before you publish just delete or make the element on each page not visible.
The template is here, Device Width Template
and a quick video explanation. Device Width Video