var CustomToolbar = new Class({
    Extends: Toolbar,
    position: function(){
        this.top = $('header').getSize().y+$('navigation').getSize().y;
        if(window.getScroll().y<this.top){ 
            this.element.morph({top: this.top});
        }else{ 
            this.element.morph({top: window.getScroll().y}); 
        }
    }
})
window.addEvent('load',function(){ 
    window.toolbar = new CustomToolbar($('toolbar'));
});