HTML5 does not reference the "Content-Type: text/html" header as enough to qualify as meaning "HTML5". HTML5 **requires** its own prolog (i.e. its basic document declaration **within** the document itself, for the HTML syntax, or its FULL document declaration for the XML/XHTML syntax). So Firefox is wrong and attempts to use HTML5 to render all HTML dialects.
2012/11/27 Simon Montagu <smont...@smontagu.org> > On 11/27/2012 11:19 AM, Behnam Esfahbod ZWNJ wrote: > >> Simon, >> >> There's no sign of HTML5 on that page. The head of the file matches all >> XHTML 1.1 requirements and passes all checks on validator.w3.org >> <http://validator.w3.org>. Now, why would Firefox follow anything from >> HTML5 spec here? >> > > As I already said, because of the Content-Type HTTP header > > >
