May 16, 2010
CSS 2.1 and CSS 3 Help Cheat Sheets
The CSS 2.1 Help Sheet covers Syntax, Font, Text, Margins, Padding, Border, Position, Background, List, Media Types and Keywords. The CSS 3 Help Sheet contains code snippets for Rounded Corners, Box Shadow, Multiple Columns, Text Shadow, RGBa, Font Face (actually, not the CSS3 property, but still include for the sake of usefulness), Box Sizing, Box Resize, Outline and Gradients.
These were kindly made available for free by Smashing Magazine.