In the test case I'm attaching, the margin-right value for the headline is from the user agent default style sheet for the h1 tag, even though the CSS class being loaded explicitly sets margin-right to a different value. The explicitly set value should override the default stylesheet. Verified with Safari 4 beta, Safari 3.2.1 and QtWebKit 4.5.1.
Created attachment 30582 [details] test case
Never mind, I just realized the test case is bogus, it's inheriting the margin-right (correctly) from the parent div, not actually from the default stylesheet.