a {
	background-image: url('adres/obrazek.png');
	background-repeat: no-repeat;
	width: 200px;
	height: 150px;
	display: block;
}
a:hover {
	background-image: url('adres/obrazek_hover.png');
	background-repeat: no-repeat;
	width: 200px;
	height: 150px;
}