var rules = {
	"ul#portfolio li" : function( el ) {
		el.onmouseover = function() {
			this.style.background = "url('images/li-bg-on2.gif') no-repeat 0 0";
			var span = getElementsByClassName( "text", "span", this );
			span[0].style.display = "block";
		},
		
		el.onmouseout = function() {
			this.style.background = "url('images/li-bg-off2.gif') no-repeat 0 0";
			var span = getElementsByClassName( "text", "span", this );
			span[0].style.display = "none";
		};
	}
};
Behaviour.register( rules );