fix layout

Author: dabeaz

_layouts/default.html

@@ -39,11 +39,9 @@ <h2 class="project-tagline">A course by @dabeaz</h2>
       {{ content }}
 
       <footer class="site-footer">
-	<span class="site-footer">
 <a rel="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/"><img alt="Creative Commons License" style="border-width:0" src="https://i.creativecommons.org/l/by-nc-sa/4.0/88x31.png" /></a><br />This work is licensed under a <a rel="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License</a>.
 <br/>
 Copyright (C) 2007-2020, <a href="https://dabeaz.com">David Beazley</a>
-	</span>
         {% if site.github.is_project_page %}
           <span class="site-footer-owner"><a href="{{ site.github.repository_url }}">{{ site.github.repository_name }}</a> is maintained by <a href="{{ site.github.owner_url }}">{{ site.github.owner_name }}</a>.</span>
         {% endif %}