Namespaces are not supported for this format.
If there is an indication prior to this sentence that the browser supports namespaces, test passes if the background is blue . Otherwise, test passes if the background is yellow .
Assertion: [Exploratory test] An xml\:lang|= selector with a value that matches an xml:lang attribute value will not produce styling for documents served as XML if the browser supports namespace declarations, but will otherwise.
If the browser does support namespaces in selectors, a message to that effect will appear in the instructions line. The expectation would be that the test would change the background to yellow only if namespaces are not supported.