Steve,
several web browsers render style sheets differently when the global DTD link is absent from the doc type of the page. To rule out any doc type ambiguity I would argue to always include the global DTD reference. Then modify the style sheet to get the look you want.
By global reference I mean http://www.w3.org/TR/html4/loose.dtd instead of a relative path like loose.dtd which is sometimes used.
/Bart