Box-shadow: 
  0 1px 2px #fff,/*bottom external highlight*/
  0 -1px 1px #666,/*top external shadow*/ 
  inset 0 -1px 1px rgba(0,0.5),/*bottom internal shadow*/ 
  inset 0 1px 1px rgba(255,255,0.8); /*top internal highlight*/

http://jsfiddle.net/NPXfe/