... Style sheet . ... Style sheets may have three different origins: author , user , and user agent . ... User . A user is a person who interacts with a user agent to view, hear, or otherwise use a document and its associated style sheet. ... A user agent that inputs style sheets must respect points 1 - 3. ... A user agent that renders a document with associated style sheets must respect points 1 - 5 and render the document according to the media-specific requirements set forth in this specification. ...