It looked like my anchors and column settings were no longer valid. Not being an expert (or even a novice) in such things, I assumed it was an issue with HTML5. I'll take formatting suggestions if you've got any...

well, perlmonks advertises html4 not html5

I don't really have any recommendations, to me it looks fine in my tests with and without the colgroups

Also, I don't see any actual anchors, you have commented out links, but no corresponding anchors like go here link

h1

h2

h3

h4

like <a href="#go here">go here link</a>
<h1>h1</h1> <h2>h2</h2> <h3>h3</h3> <h4>h4</h4>
<a name="go here">You are here anchor </a>
[download]