A cascading style sheet (CSS) is a set of rules applied to a web page to control its presentation or appearance. A rule assigns properties to one or more elements. An element is a structural feature of a document, such as a heading or a paragraph. The properties, such as font, color, and size, define the appearance of that element. A style sheet is a collection of rules that can be applied to a single web page or an entire web site. Style sheets are said to cascade because more than one style sheet can control the presentation of a web page.

Style Structure

A style is made of a selector and one or more declarations. The selector is the element to which a style is being assigned. The declaration defines the properties and values assigned to the element. A property is a characteristic...