if ( window.event.y < 55 ) document.getElementById("kasten").style.top=15;
else {
if ( window.event.y > 445 ) document.getElementById("kasten").style.top=424;
else document.getElementById("kasten").style.top=window.event.y-45;
}
if ( window.event.x < 95 ) document.getElementById("kasten").style.left=55;
else {
if ( window.event.x > 465 ) document.getElementById("kasten").style.left=464;
else document.getElementById("kasten").style.left=window.event.x-45;
}