CSS

CSS, or cascading style sheets, is an acronym. It is a language for creating style sheets that describe the layout and appearance of markup-language documents. It gives HTML an additional feature. Typically, it works with HTML to modify the look and feel of online pages and user interfaces. Any XML document type, including plain XML, SVG, and XUL, can be used with it.

To construct user interfaces for web apps and many mobile applications, most websites combine CSS, HTML, and JavaScript.