window.addEvent('domready', function(){
 $$('.navigation_item').each(function(el) {
  el.addEvent('mouseover', function() {
	var navigation_class = this.getProperty('class').replace(/inactive/g,'hover');
	this.setProperty('class',navigation_class);
  });
  el.addEvent('mouseout', function() {
	var navigation_class = this.getProperty('class').replace(/hover/g,'inactive');
	this.setProperty('class',navigation_class);
  });
 });
});