Description

Cascading Style Sheets (CSS) make it possible to seperate the presentation from the content of a website to a great extent. CSS code consists of declarations that determine the style of elements on a website. Current web standards promote using CSS for creating the layout of a site, as opposed to using tables.

The Specification by the W3C can be found here: http://www.w3.org/TR/CSS21/

Resources

Learning CSS by the W3C. Links to online resources: http://www.w3.org/Style/CSS/learning
A concise tutorial of the important features of CSS: http://brainjar.com/css/using/
Positioning with CSS: http://brainjar.com/css/positioning/
What you need to know about the float property: http://www.smashingmagazine.com/2009/10/19/the-mystery-of-css-float-property/