For relying on XML_Util to parse single quotes into &apos between SCRIPT tags, even if you mark it as CDATA.
Browsers need a stab in the face for not parsing ' into a single quote in a SCRIPT tag.
Browsers need a stab in the face for not grokking <script src="" type="" /> [ok, ok, I know, I was serving it with the wrong mime type, but HELL...]
And finally, people, everywhere, need a stab in the face for (mis)use of CSS.
As you can tell, it's been a long hard day of fixing other people's markup.