Columns touching, Logo overlapping mobile menu, no mouesover on mobile devices

Hi, on www.vflberghausen.de i am using the three column layout for the homepage. I have placed a calendar (Spider Event Calendar) in secondary sidebar and different widgets in the primary sidebar. When you resize the browser window (tested under Windows with IE, FF, Chrome and Safari) in the last view before changing from three column to single column layout, the secondary widget bar touches the content column (in mobile Safari it even overlaps, when using the standard wordpress calendar). Is there a way to prevent this? Second i have a logo with a transparent canvas (to position it correctly above the page) but the logo overlaps the mobile menu on my iPad and iPhone. What can i do? And last, i have created a menu and some top menu items (Abteilungen, Service), will not drop down on mobile devices. i built the menu with custom links for these items and then deleted the link because i dont want them to be clickable. Hope, i explained everything understandable. Thanks, Juergen