var homerules = {
	'ul.homeimg li a span' : function(el) {
		new Effect.Opacity(el.id, {duration: 0.8, from: 1, to: 0});
    }
};

Behaviour.register(homerules);

var opacity = 0.7;
var duration = 0.5;
function fadeIn(elementID) {
	new Effect.Opacity(document.getElementById(elementID), {duration: duration, from: 0, to: opacity});	
}

function fadeOut(elementID) {
	new Effect.Opacity(document.getElementById(elementID), {duration: duration, from: opacity, to: 0});
}

var homeImgRules = {
	'ul.homeimg li a' : function(el) {
		addCorner(el, 'topleft');
		addCorner(el, 'topright');
		addCorner(el, 'bottomright');
		addCorner(el, 'bottomleft');
	}
};

Behaviour.register(homeImgRules);

function addCorner(linkEl, classNameStr) {
	var corner = document.createElement("div");
	corner.className = classNameStr;
	linkEl.appendChild(corner);
}