lang="" vs meta Content-Language
Assertion holds if you see green below.
This test is only valid if the user agent recognises the meta Content-Language and html lang declarations, and :lang works.
|Ignore this test. (:lang not supported)|
Assertion: If the meta Content-Language element contains a language declaration but the html element uses an empty lang attribute, the UA will not recognize the language declared in the meta Content-Language element.
Red means the HTTP had precedence.