background-color: #eee;
background-image: linear-gradient(top, #fff 0%, #eee 300px); /* W3C */
background-image: -moz-linear-gradient(top, #fff 0%, #eee 300px); /* FF3.6+ */
background-image: -webkit-linear-gradient(top, #fff 0%, #eee 300px); /* Chrome10+,Safari5.1+ */
This is according to the current Mozilla documentation: https://developer.mozilla.org/en/CSS/-moz-linear-gradient.
I’ve confirmed that it works in Firefox 3.6 and Chrome 15.