Hi! I just noticed that my website, andrea.pappacoda.it, triggers a warning from the bug meter: HTML warning: line 1, The required DOCTYPE declaration is missing. Handling as HTML4. My website though is an XHTML page, served with the application/xhtml+xml media type, and thus requires no DOCTYPE, which is only required in the "HTML syntax" of HTML. See: - https://html.spec.whatwg.org/dev/xhtml.html#the-xhtml-syntax - https://html.spec.whatwg.org/dev/syntax.html#syntax I couldn't find a way to add this to the bug tracker, so I'm sending it here. Please keep me Cc'd as I'm not subscribed :) Bye!