Test that CSSStyleDeclaration.setProperty() can unset the 'important' flag On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE". div.style.setProperty('color', 'red', 'important') PASS div.style.getPropertyValue('color') is "red" PASS div.style.getPropertyPriority('color') is "important" div.style.setProperty('color', 'green', null) PASS div.style.getPropertyValue('color') is "green" PASS div.style.getPropertyPriority('color') is "" PASS successfullyParsed is true TEST COMPLETE