CSS3 is completely backwards compatible, so you will not have to change existing designs. Browsers will always support CSS2.
CSS3 is split up into "modules". The old specification has been split into smaller pieces, and new ones are also added.
Some of the most important CSS3 modules are:
The CSS3 specification is still under development by W3C.
However, many of the new CSS3 properties have been implemented in modern browsers.
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