// JavaScript Document
// requires mootools release 83 or above
window.onload = function() {

    
    $$('a.navbutton').each(function(el){
    
        el.addEvent('mouseover',function(){
            // actual mouseover action
            this.firstChild.src = this.firstChild.src.replace(/off/g,'on');
            // effect is optional
            this.effect('opacity').custom(.3,1);
        });
        
        el.addEvent('mouseout',function(){
            // actual mouseover action
            this.firstChild.src = this.firstChild.src.replace(/on/g,'off');
            // effect is optional
            this.effect('opacity').custom(.3,1);
        });
    
    });

};