function stessa_altezza(className) {
    cols = getElementsByClassName(className);
    var max = 0;
    for(var i=0; i<cols.length; i++) {
        if(cols[i].clientHeight > max) max = cols[i].clientHeight;
    }
    for(i=0; i<cols.length; i++) {
        cols[i].style.height = max + "px";
    }
    for(i=0; i<cols.length; i++) {
        if(cols[i].clientHeight > max) {
            offset = cols[i].clientHeight - max;
            cols[i].style.height = (parseInt(cols[i].style.height)) - offset + "px";
        }
    }
}