In your demo version, if I follow this link it goes to your page.  Doesn't that mean in the real site (http://www.astropy.org/astropy-tutorials/blah/blah.html), this href will go to "www.astropy.org", but it should go to http://www.astropy.org/astropy-tutorials, right?  So maybe just change the href to "http://tutorials.astropy.org"?