<!DOCTYPE html>
<script>
    onload = function() {
        var elm = document.getElementById('elm');
        document.body.offsetTop; // trigger layout
        elm.style.display = 'block';
    }
</script>
<p>Insert a block in the middle of column content.</p>
<p>There should be two lines below with the word "PASS", with large letter spacing.</p>
<div style="-webkit-columns:4; -webkit-column-gap:0; width:4em;">
    P<br>P<br>A<br>
    <div id="elm" style="display:none;">A</div>
    S<br>S<br>S<br>S
</div>