Cascading Style Sheets (in short, CSS) is a language used to describe the presentation of a web page. CSS was developed by W3C in 1996 as a successor of DSSSL. The first draft was proposed in 1994 by Hakone Wium Lie.
CSS is a list of directives (the so-called rules) which determine how a Web page is to be displayed by a Web browser. Using the language, one can specify various properties of HTML elements, such as font family, text color, margins, spacing, or even the position of the element.
CSS was designed to separate the document’s structure from its presentation. This separation increases the accessibility of the site, reduces the complexity of the document coding, and simplifies any possible future changes to the site.