<!DOCTYPE html>
<script>
onload = function() {
document.body.offsetTop; // trigger layout
document.getElementById('elm').className = "x";
}
</script>
<style>
.x::after { display:block; -webkit-column-span:all; background:yellow; content:".........."; }
</style>
<p>Test adding an ::after pseudo element that's a spanner. The DOM node is followed by more content,
so we need to split the existing column row into two.</p>
<p>There should be three rectangles with identical sizes below. The first and third one
should be blue with nothing inside. The second one should be yellow with some dots
inside.</p>
<div style="-webkit-columns:4; line-height:100px; background:blue;">
<span id="elm"> </span>
</div>