[lang="es-MX"], lang="es"

Ignore this test. (lang= with lang attribute is not supported)
You can only get meaningful results for this test if the lang= selector works with the lang attribute, since it checks a detail with regard to that support.

Test passes if you see green below.

Text

Assertion: A lang= value will not match a lang attribute value when the former contains more subtags.

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HTML5

selectors-037
Result summary & related tests