background: #999; /* for non-css3 browsers */

filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#cccccc', endColorstr='#000000'); /* for IE */
background: -webkit-gradient(linear, left top, left bottom, from(#ccc), to(#000)); /* for webkit browsers */
background: -moz-linear-gradient(top,  #ccc,  #000); /* for firefox 3.6+ */

http://www.webdesignerwall.com/tutorials/cross-browser-css-gradient/

Cross-Browser CSS Gradient

CSS