<!DOCTYPE html>
<p>Check that the top margin on a block around a spanner inside an auto-filled multicol container
    isn't lost.</p>
<p>Below there should be a black square.</p>
<div style="-webkit-columns:3; -webkit-column-gap:0; column-fill:auto; width:600px; height:2000px;">
    <div style="margin-top:200px; border-top:100px solid black;">
        <div style="-webkit-column-span:all; width:200px; height:100px; margin:auto; background:black;"></div>
        <div></div>
    </div>
</div>