Introduction to CSS3
CSS3 is fully backward compatible, so you don't have to change your existing design.
CSS3 Modules
CSS3 is split into "modules". The old specification has been split into smaller pieces, and new ones have been added.
Some of the most important CSS3 modules are as follows:
Selector
box model
backgrounds and borders
text effects
2D/3D conversion
animation
Multi-column layout
User Interface
CSS3 Recommendations
The W3C's CSS3 specification is still under development.
However, new browsers now support CSS3 properties.