Cascading Style Sheet, level 1 (CSS1)
CSS1 (Cascading Style Sheet, level 1) is the recommendation from the World Wide Web Consortium (W3C) for a standard cascading style sheet specification.
A cascading style sheet (CSS) is a style sheet derived from multiple sources with a defined order of precedence where the definitions of a style element conflict. CSS1 describes the recommended approach for Web page designers and browser developers to adhere to.