Scrolling problem with secondary menu and Safari on Ipad

Hallo. I bought Pro Adventurous theme Premium Version. Please refer to my web site at the following url: www.viadellaseta.net Unfortunately I'm finding the following problems under Ipad Air and Safari: often the secondary menu disappears covered by the header zone (the zone with title of site and primary menu). In addition when I open the secondary menu (voice "paesi" that is italian word for "countries") the menu doesn't scroll (moving the finger only the main page scrolls down). I'd like block the header zone... Can you help me? Thank you very much. Alessandro