<!DOCTYPE html>
<html>
<head>
<style>
.columns { -moz-column-count:2; -webkit-column-count:2; column-count:2; column-fill:auto; -webkit-column-gap:20px; border:2px solid black; height:300px; }
.block { height:200px; background-color:purple; }
</style>
</head>
<body>
The two purple rectangles below should both be at the top of their columns.  If one is lower than the other, than the test has failed.
<div class="columns">
<div class="block" style="margin-bottom:200px"></div>
<div class="block"></div>
</div>