function $N(element) {
    /*if(typeof element == 'string') {
        element = document.getElementsByName(element)[0];
    }
    return Element.extend(element);*/
    return $('#'+element);
}

function checkOfferForm(o) {
    if($N('Offers-email_invoice').val()=='') {
        alert(lang_pleaseMail);
        return false;
    }
    if($N('Offers-email_invoice_2').val()=='') {
        alert(lang_pleaseMailAgain);
        return false;
    }
    if($N('Offers-name_invoice').val()=='') {
        alert(lang_pleaseName);
        return false;
    }
    if($N('Offers-phone_invoice').val()=='') {
        alert(lang_pleaseTel);
        return false;
    }
    if($N('Offers-email_invoice').val()!=$N('Offers-email_invoice_2').val()) {
        alert(lang_pleaseCorrectMail);
        return false;
    }
    $(o).parents('form').trigger('submit');
    $('#blackWindow').hide();
    $('#offerWindow').hide();
    alert('Ihr Angebot wird Ihnen in den nächsten Minuten zugesandt.');
}