<head>
<style>
#container { border:2px solid blue; }
#container:hover { border:5px solid lime; }
#one { border:2px solid orange }
</style>
</head>
<body>
<div id="container" style="position:absolute;">
<div id="one" style="float:left">One</div><div style="float:left;">Two</div>
</div>

<script>
document.body.offsetWidth;
document.getElementById('one').style.cssFloat=''
</script>