Cascading Style Sheets(CSS) An extension to {HTML} to allow styles, e.g. colour, {font}, size to be specified for certain elements of a {hypertext} document. Style information can be included in-line in the HTML file or in a separate CSS file (which can then be easily shared by multiple HTML files). Multiple levels of CSS can be used to allow selective overriding of styles. {Home (http://www.w3.org/Style/CSS/)}. (2000-07-26)