$$('.dark').addEvent('mouseover', function() { this.setStyle('background', '#ffffdf') });
$$('.dark').addEvent('mouseout', function() { this.setStyle('background', '#ffeedd') });
$$('.light').addEvent('mouseover', function() { this.setStyle('background', '#ffffdf') });
$$('.light').addEvent('mouseout', function() { this.setStyle('background', '#F4FDFA') });