lang="..." vs lang=""

Test passes if you see green below, and no message to ignore it.

This test is only valid if the user agent recognises html lang declarations, and :lang works.

Ignore this test. (:lang not supported) 

Assertion: If an element contains a language attribute with an empty value, the value of a language attribute higher up the document tree will no longer be applied to the content of that element.

Notes:

Red means that the formerly declared language was still inherited, despite the lang='' attribute.

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HTML5

language-declarations-018
Result summary & related tests