var minH=500;
var defX=-512;
function setPic(){
  if(document.getElementById('bildBox')){
    if(document.getElementsByTagName('body')[0].offsetHeight<minH){
      var newPos=minH-document.getElementsByTagName('body')[0].offsetHeight+defX;
      document.getElementById('bildBox').style.top= newPos+'px';
    }else document.getElementById('bildBox').style.top= defX+'px';
  }else if(document.getElementById('cont')){
    var picHeight=document.getElementById('cont').getElementsByTagName('img')[0].offsetHeight;
    if((document.getElementsByTagName('body')[0].offsetHeight-document.getElementById('bottom').offsetHeight)<picHeight){
    //alert(document.getElementById('cont').getElementsByTagName('img')[0].offsetHeight);
      var newPos=document.getElementsByTagName('body')[0].offsetHeight-document.getElementById('bottom').offsetHeight;
      document.getElementById('cont').style.top= -newPos+'px';
    }else document.getElementById('cont').style.top= -picHeight+'px';
  }
}
window.onload=setPic;
window.onresize=setPic;