CSS3 Previews

Borders

border-color
border-image
border-radius
box-shadow

Backgrounds

background-origin and background-clip
background-size
multiple backgrounds

Color

HSL colors
HSLA colors
opacity
RGBA colors

Text effects

text-shadow
text-overflow
word-wrap

User-interface

box-sizing
resize
outline
nav-top, nav-right, nav-bottom, nav-left

Selectors

attribute selectors

Basic box model

overflow-x, overflow-y

Generated Content

content

Other modules

CSS3 Transitions
media queries
multi-column layout
Web fonts
speech