Hey!
I fixed this by setting the landing page slider to ‘banner image’ (with a large banner image) and then having the other pages’ header images as small as I could make them (header > content > header image height), while still containing the page titles. This seems to work in terms of minimising the header of other pages for mobile display, although I’m struggling with having the theme work for mobile in other respects (menu and page title from the header are all over the place!!)
Hope this helps! 🙂
-Margot