All what happens is onload="printPretty()" appears on the page. Here is my code
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset=utf-8>
<title> SITE </title>
<link rel="stylesheet" type="text/css" href="/static/css/main.css" />
<link href="/blog/templates/prettify.css" type="text/css" rel="stylesheet" />
<script type="text/javascript" src="/blog/templates/prettify.js"></script>
<!--[if lt IE 9]>
<![endif]-->
</head>
<body>
<header><h1><a href="/blog" title="Homepage"> site<3 </a></h1></header>
<nav>
<a href="/blog" class="projects"> Home</a>
<a href="/blog/tag/projects" class="projects"> Projects</a>
<a href="/blog/blogarchives/" class="index"> Blog</a>
<a href="/blog/about" class="about"> About</a>
</nav>
<section>
<article>
<!-- blog post -->
{% block content %}
{% endblock %}
</article> <!-- blog post ends -->
</section>
<footer>
<div class="about">
</div>
<div class="social">
<a href="/blog/feed" class="rss"> RSS Feed</a> |
<a href="#">Twitter</a> |
<a href="#">LinkedIn</a> |
<a href="#">Github</a> |
<a href="#">Facebook</a> |
<a href="#">Email</a>
</div>
<div class="poweredby">
</div>
</footer>
onload="prettyPrint()"
</body>
</html>