Homepage slider images cut off at top and bottom

Homepage slider images cut off at top and bottom, mid section of image appears beneath header as if the page was scrolled though it wasn’t. This happens on tablets in landscape view. Does anybody have an idea why? When I resize the window on my Mac everything scales just fine. Most test sites show the site working fine on tablets but when tested for real the slider images are cut off. site: http://roselandquartet.nl

thanx in advance!