function tieudiem_forward() {
    document.getElementById('tieudiem_content_animation').style.position = 'absolute';
    document.getElementById('tieudiem_content').style.position = 'relative';
    document.getElementById('tieudiem_content').style.height = (eval(document.getElementById('tieudiem_content_animation').offsetHeight)) + 'px';
    if (currenttab < maxtab) {
        var leftpx = currenttab * (-673);
        $('#tieudiem_content_animation').animate({ left: leftpx }, 673);
        currenttab++;
    }
    if (currenttab > maxtab) currenttab = maxtab;
}
function tieudiem_backward() {
    if (currenttab > 1) {
        var leftpx = (currenttab - maxtab + 1) * (-673);
        $('#tieudiem_content_animation').animate({ left: leftpx }, 673);
        currenttab--;
    }
    if (currenttab < 1) currenttab = 1;
}