http://jsfiddle.net/cEv2S/ - My index page, fails to validate via xhtml 1.1 standards
I receive the validation error " Line 38, Column 6: element "nav" undefined "
<div id="header">Leon's CS150 Assignment</div>
<nav> <!-- this is the line quoted in my error message -->
<div>
<a class="Menu-Item" href="#">Home</a>
<a class="Menu-Item" href="about.html">About</a>
<a class="Menu-Item" href="cv.html">CV</a>
<a class="Menu-Item" href="../wordpress">Wordpress</a>
<a class="Menu-Item" href="../webshop/catalog">Webshop</a>
</div>
</nav>
You are using the incorrect DOCTYPE for HTML5.
The <nav>
element is defined in the HTML5 spec, but your document is not using HTML5.
You need to use the following doctype
<!DOCTYPE html>