CSS3 Transitions

div {
	width:70px;
	height:40px;
	background-color:#000000;
	color:#FFFFFF;
	-moz-transition: width 0.3s ease; /* Firefox 4 */
	-webkit-transition: width 0.3s ease; /* Safari and Chrome */
	-o-transition: width 0.3s ease; /* Opera */
	-ms-transition: width 0.3s ease; /* IE (not supported) */
	transition: width 0.3s ease;
}
div:hover
{
	width:120px;
	-moz-transition: width 0.3s ease; /* Firefox 4 */
	-webkit-transition: width 0.3s ease; /* Safari and Chrome */
	-o-transition: width 0.3s ease; /* Opera */
	-ms-transition: width 0.3s ease; /* IE (not supported) */
	transition: width 0.3s ease;
}