window.onload = function() {
	capa = new Image();
	capa.src = 'images/capa.gif';
	capa_over = new Image();
	capa_over.src = 'images/capa_over.gif';
	about = new Image();
	about.src = 'images/about.gif';
	about_over = new Image();
	about_over.src = 'images/about_over.gif';
	contact = new Image();
	contact.src = 'images/contact.gif';
	contact_over = new Image();
	contact_over.src = 'images/contact_over.gif';
	document.getElementById('capa').onmouseover = function() {
		document.getElementById('capa').src = capa_over.src;
	}
	document.getElementById('capa').onmouseout = function() {
		document.getElementById('capa').src = capa.src;
	}
	document.getElementById('about').onmouseover = function() {
		document.getElementById('about').src = about_over.src;
	}
	document.getElementById('about').onmouseout = function() {
		document.getElementById('about').src = about.src;
	}
	document.getElementById('contact').onmouseover = function() {
		document.getElementById('contact').src = contact_over.src;
	}
	document.getElementById('contact').onmouseout = function() {
		document.getElementById('contact').src = contact.src;
	}
}