<!DOCTYPE html>
<p>There should be a <em>square</em> below.</p>
<div style="-webkit-columns:3; width:12em;">
    <br><br><br><br><br>
    <div style="-webkit-column-span:all; border:1em solid; line-height:1em; background:yellow;">
        <br>
        <br>
        <br>
        <br>
        <br>
        <br>
        <br>
        <br>
        <br>
        <br>
    </div>
    <br><br><br><br><br>
</div>
