/*Proper rounded corners for Gecko(Firefox) */
-moz-border-radius:8px;
/*Proper rounded corners for Webkit(Safari, Chrome) */
-webkit-border-radius:8px;
/*Proper rounded corners for KHTML, Webcore (Konquerer, etc.) */
-khtml-border-radius:8px;
/*Use graceful degradation for time when browser specific properties are phased out  */
border-radius:8px;
 
/* Setting different corner values, Safari doesn't support shorthand values */
-webkit-border-top-left-radius:5px;
-webkit-border-top-right-radius:5px;
-webkit-border-bottom-left-radius:0;
-webkit-border-bottom-right-radius:0;
/*Use graceful degradation for time when browser specific properties are phased out  */
border-bottom-right-radius:0;
border-bottom-left-radius:0;
 
/*Otherwise use shorthand */
-moz-border-radius:5px 5px 0 0;
border-radius:5px 5px 0 0;
 
/* Btw, F you IE! */

CSS 3 PROPER BORDER RADIUS USAGE

CSS3

CSS