Rewrite layout to look like www.php.net redesign

The markup and CSS is rewritten from the www markup/css.
It is dramatically simpler, yet offering all the same benefits
(e.g. "responsive") - plus no need for js workarounds for anchors
Need to work on migrating it over to www
Improve .secondscreen on tiny viewports

Make the sidebar/search box cover a full line when it gets line-wrapped
on tiny viewports.
Make sure it doesn't overlap the content by doubling the padding-top
when we need to linewrap