.bouton{
	display:block;
	width:760px;
	height:570px;
	background:url('../images/gatto.png') no-repeat;
	cursor:pointer;
}

.bouton span.hover{
	display:block;
	width:760px;
	height:570px;
	background:url('../images/gatto.png') no-repeat;
	cursor:pointer;
	background-position:bottom;

}