CSS: border-radius and -moz-border-radius
1. Rounded Corners for Firefox, Safari & Chrome
.rounded-corners {
-moz-border-radius: 20px;
-webkit-border-radius: 20px;
-khtml-border-radius: 20px;
border-radius: 20px;
}
2. Border Radius and Other special effects
http://www.the-art-of-web.com/css/border-radius/
3. Border radius for Interner Explorer
http://jonraasch.com/blog/css-rounded-corners-in-all-browsers