var viewportwidth;
 var viewportheight;

 // the more standards compliant browsers (mozilla/netscape/opera/IE7) use window.innerWidth and window.innerHeight

 if (typeof window.innerWidth != 'undefined')
 {
      viewportwidth = window.innerWidth,
      viewportheight = window.innerHeight
 }

// IE6 in standards compliant mode (i.e. with a valid doctype as the first line in the document)
 else if (typeof document.documentElement != 'undefined'
    && typeof document.documentElement.clientWidth !=
     'undefined' && document.documentElement.clientWidth != 0)
 {
       viewportwidth = document.documentElement.clientWidth,
       viewportheight = document.documentElement.clientHeight 
 }

 // older versions of IE
 else
 {
       viewportwidth = document.body.clientWidth,
       viewportheight = document.body.clientHeight
 }

abstand = viewportheight - 20
hoehe = viewportheight
hoehe1 = 50 + viewportheight / 2
hoehe2 = hoehe1
hoehe3 = viewportheight / 20
hoehe5 = -10 - viewportheight / 10