<html xmlns="http://www.w3.org/1999/xhtml">
<head>
</head>
<body >
<div style="-moz-column-count: 2; border: 1px solid green">
<span>AAAA
<div style="float: left;border: 1px solid blue">BBBB
</div>
</span>
</body>
</html>