init_adventskalender = function() {
    var ak = $('adventskalender');
    ak.getElements('.box').each(function(e) {
        e.addEvent('mouseover', function(n) {
            e.setStyles({'background': '#fff',
                         'opacity': 0.5});
        });
        e.addEvent('mouseout', function(n) {
            e.setStyles({'background': 'none',
                         'opacity': 1});
        });
    });
}

//window.addEvent('domready', init_adventskalender);