<!DOCTYPE html>
<html>
    <head>
        <script>
            function test() {
                var elm = document.getElementById('elm');
                elm.offsetTop; // trigger layout
                elm.style.height = '14em';
            }
        </script>
    </head>
    <body onload="test()">
        <p>Below there should be <em>one</em> column with 7 lines.</p>
        <div id="elm" style="-webkit-columns:3; columns:3; column-fill:auto; orphans:1; widows:1; height:4em; line-height:2em;">
            line<br>
            line<br>
            line<br>
            line<br>
            line<br>
            line<br>
            line<br>
        </div>
    </body>
</html>