A CSS style sheet is like using style codes in Word. Different styles are developed and used throughout the document. One style sheet can be developed for a particular type of document. For example, for corporate documents, a very plain stylesheet would be used, a font such as Arial or Times Roman, all black 12 point for the body and 14 or 16 point for the headings. Other style sheets can be developed for articles or blogs.
Legal documents can often be found on corporate web pages, either as an html file or a pdf file. They must adher to very specific standards, depending on the type of document. Some types of legal documents are pleadings, interrogatories, wills, deeds, patents and trust documents. The Court dictates styles for pleadings and different Courts can require different size headings, fonts, margins and so on.
The US Patent Office also has strict style guidelines for patents. Usually, Times Roman or Arial font, 12 point is requested for the final, line height, 14 point. Headings are usually bold and underlined. The main heading is centered and all caps.