CSS (Cascading Style Sheets) is a declarative language that controls how webpages look in thebrowser.

The browser applies CSS style declarations to selected elements to display them properly. A style declaration contains the properties and their values, which determine how a webpage looks.

CSS is one of the three core Web technologies, along withHTML andJavaScript. CSS usually stylesHTML elements, but can be also used with other markup languages likeSVG orXML.

A CSS rule is a set ofproperties associated with aselector. Here is an example that makes every HTML paragraph yellow against a black background:

/* The selector "p" indicates that all paragraphs in the document will be affected by that rule */p {  /* The "color" property defines the text color, in this case yellow. */  color: yellow;  /* The "background-color" property defines the background color, in this case black. */  background-color: black;}

"Cascading" refers to the rules that govern how selectors are prioritized to change a page's appearance. This is a very important feature, since a complex website can have thousands of CSS rules.

See also

• Learn CSS
• The CSS documentation
• CSS on Wikipedia
• The CSS Working Group current work