Scrolling problem

I have been working on this theme for 2 weeks and i really like all the capabilities of catch full screen free. I am considering to purchase pro version but i am facing a problem when i scroll down and up, the sections does not display correctly. When you scroll down the sections appears fine but if you scroll back(up), the section appears to be overlap by the header (Main menu) hiding the section headings. It is also happening in your theme demo. https://catchthemes.com/demo/catch-fullscreen/#section0 Looking forward to your reply.