<!DOCTYPE html>
<style>
.spanner { -webkit-column-span:all; }
.none { display:none; }
</style>

<p>Insert a spanner between two absolutely positioned elements.</p>
<p>There should be three lines below, numbered from 1 to 3.</p>
<div style="-webkit-column-count:2;">
    1
    <div style="-webkit-column-span:all;">2</div>
    <div style="position:absolute;"></div>
    <div id="becomesSpanner" class="none">3</div>
    <div style="position:absolute;"></div>
</div>

<script>
onload = function() {
  document.body.offsetTop;
  document.getElementById("becomesSpanner").className = "spanner";
}
</script>