<body onload="test()">
<div style="font-family: Ahem; font-size: 50px; color: red;">
<span id="float" style="float: left; color: green; position: relative;">Y</span>Z
</div>
<script>
function test()
{
document.body.offsetTop;
document.getElementById("float").style.position = "absolute";
}
</script>
</body>