var Shadow = Class.create({
	initialize: function(el, min, max, duration) {
		this.element = $(el);
		this.min = (min == null)?0.3:min;
		this.max = (max == null)?1:max;
		this.duration = (duration == null)?0.5:duration;
		this.element.observe('mouseover', this.show.bindAsEventListener(this));
		this.element.observe('mouseout', this.hide.bindAsEventListener(this));
		this.hide();
	},
	show: function() {
		new Effect.Opacity(this.element, {duration: this.duration, from: this.min, to: this.max});
	},
	hide: function() {
		new Effect.Opacity(this.element, {duration: this.duration, from: this.max, to: this.min});
	}
});