<!DOCTYPE html>
<html>
<head>
<style>
#outer {
-moz-column-count: 2;
}
#inner {
border: 1px solid green;
}
</style>
<style id="s">
#inner {
float: right;
height: 1em;
}
</style>
</head>
<body onload="document.getElementById('s').disabled = true;">
<div id="outer"><div id="inner"></div></div>
</body>
</html>