.boek_nu {
	float:right;
	width: 93px;
	height: 33px;
	background-image: url("http://thenextspeaker.com/wp-content/uploads/2010/07/registreer-normal.png");
}

.boek_nu:hover {
	background-image: url("http://thenextspeaker.com/wp-content/uploads/2010/07/registreer-hover.png");
	cursor: pointer;
}