spielerei mit Navigation(2)

#nav_container
{
position: absolute;
top: 100px;
left: 50%;
margin-left: -400px;
width: 800px;
height: 30px;
background-color: #FF0000;
background-image: none;
background-repeat: no-repeat;
background-position: center;
}

<script type="text/javascript">


if (window.event)
{
if (document.captureEvents)
{
document.captureEvents(Event.MOUSEMOVE);
} else
{
window.captureEvents(Event.MOUSEMOVE);
};
};

document.onmousemove = changeState;

function changeState()
{
var ScrollY = 0;
if( document.body && ( document.body.scrollLeft || document.body.scrollTop ) )
{
ScrollY = document.body.scrollTop;
}
else
if( document.documentElement && ( document.documentElement.scrollLeft || document.documentElement.scrollTop ) )
{
ScrollY = document.documentElement.scrollTop;
}
if(ScrollY >= 100)
{
document.getElementById('nav_container').style.position = "fixed";
document.getElementById('nav_container').style.top = "0px";
}
else
{
document.getElementById('nav_container').style.position = "absolute";
document.getElementById('nav_container').style.top = "100px";
}
}


</script>