<!DOCTYPE html>
<p>Below there should be a multicol container in vertical-lr
    writing-mode. There should be a row of columns, followed by a spanner,
    followed by another row of columns.</p>
<div style="-webkit-columns:2; -webkit-column-rule:2px solid; -webkit-column-gap:1em; -webkit-writing-mode:vertical-lr; line-height:2em; height:13em; background:yellow;">
    first<br>
    first<br>
    first<br>
    second<br>
    second<br>
    <div style="-webkit-column-span:all; border:5px solid; padding:5px;">
        I am a spanner. I don't care about your precious columns.
    </div>
    first<br>
    first<br>
    second<br>
</div>