Introduction

Cascading Style Sheets (CSS) is a style sheet language for a document written in a markup language. It is widely used for defining layout or presentation of HTML documents.

A style sheet is made up of a set of rules. A rule or rule set consists of a selector followed by a declaration block of property/value pair(s). For example, the below rule selects paragraph elements followed by a declaration within braces made up of a property (color) and its value (red)

				
				p {
					color: red;
				}
				
			

Each declaration ends with a semicolon. A single rule can have one or more declarations, placed inside braces for a selected element

				
				p {
					color: red;
					font-size: 12px;
				}
				
			

CSS rules can be applied inline via the style attribute, or embedded within the style element, or linked to an external stylesheet inside the link element.