<!DOCTYPE html>
<p>Test that an empty block between spanners doesn't affect margin collapsing.</p>
<p>There should be a blue square below.</p>
<div style="-webkit-columns:3; width:10em; background:blue;">
    <div style="-webkit-column-span:all; margin-bottom:5em; background:white;"></div>
    <div></div>
    <div style="-webkit-column-span:all; margin-top:5em; background:white;"></div>
</div>