CSS3 introduction
CSS3 is fully backward compatible, so you don’t have to change your existing design.
CSS3 module
CSS3 is split into “modules”. The old specification has been split into small pieces and new ones have been added.
Some of the most important CSS3 modules are as follows:
Selector
Box model
Background and border
Text special effects
2D/3D conversion
Animation
Multi-column layout
User interface
CSS3 recommendation
The W3C CSS3 specification is still under development.
However, new browsers now support the CSS3 attribute.