Safari web development div display none stays partially on screen

I've been working on a drop down menu on a website. It works fine in other browsers but not Safari. When trying to close a menu (display none, visibility hidden and opacity 0), the div or the ul (tried both) in some cases stays partially on screen (looks random), screenshot enclosed: In this case one menu was opened, then another, so that the first one should close and disappear instead of staying partly visible below the new one. Anybody ever met similar display problems? Looks like the first, second and last menus work, the three in between not, but I can't figure out the difference. hami.fi