At various points in the document offered in section "Example Document", markup is mentioned without being escaped.  In one case, i.e.

  "Polyglot markup introduces undeclared (native) default namespaces 
      for the the root SVG element (<svg>)"

this makes the document you get if you simply copy the visible text not be well-formed XML.  Here (and e.g. for "<p></p> not <p />") the '<' should be replaced with '&lt;'.

Also wrt this example, it's probably misleading to leave unescaped link markup in the displayed text.  I would suggest simply wrapping the entire exact SamplePage.html document (which itself is well-formed) in a CDATA-section in your source HTML, then all the above problems will go away.