Cascading Style Sheet is a short form of CSS. In simple terms, web page elements, structure, size, shape, position, color, etc., to determine the mobility strategy is simple CSS.
Why do you need CSS?
There was a time when only the HTML of a Web site was designed. He said the design of a web page font color, size, color cells in the table, the background color of the page, and the required image was meant Merger. And each page separately for each component color, size was not. Which was a complex process, and time-consuming affair. If a web site is now more similar to 1000, or even if pages are completely designed using a single CSS file.