//kolommen even hoog maken bv. equalHeight($('.content').find('article'));

equalHeight.js

    function equalHeight(group) {
        var tallest = 0;
        if(group.length){
            group.each(function () {
                var thisHeight = $(this).height();
                if (thisHeight > tallest) {
                    tallest = thisHeight;
            }
            });
            group.height(tallest);
        }
    }