CSS
Also called: Cascading StyleSheet or stylesheet
CSS stands for Cascading StyleSheet. The standard is used for the layout and design of Web pages constructed from HTML. A CSS file can be used to determine what colors, fonts, background colors, margins, etc., certain parts of a Web page should be displayed in the visitor's Web browser.
By making a consistent distinction between HTML document (structure) and stylesheet (design) when formatting Web pages, Web pages contain less code, are easier to access for search engines, for example, and it is also easier to change the design of a Web site in the future in one go.