window.addEvent('domready', function(){
	
	var sponsors = $$('#sponsors a').setStyle('opacity', 0.5); // Set opacity to 0.5 for grayscale image
	
	sponsors.set('tween',{duration:100, wait:false}).addEvents({
		
		//On mouseenter
		'mouseenter': function(){
			this.setStyle('background-position','0 -214px'); //Reveal color image
			this.get('tween').start('opacity',1); //set opacity to 1
		},		
		
		//on mouseleave
		'mouseleave':function(){
			this.setStyle.delay(100,this,['background-position','0 0']); //set back initial background-position for grayscale image
			var tween =  this.get('tween');
			tween.start.delay(100, tween,['opacity',0.5]); //set back initial opacity
		}
		
	});
});