function updateDob() {
    var day = document.getElementById('dob_day').value;
    var month = document.getElementById('dob_month').value;
    var year = document.getElementById('dob_year').value;
    
    if (day > 0 && month > 0 && year >= 1900) {

        // Calculate birth date
        var born = new Date(year, month-1, day);

        // Calculate limit date
        var now = new Date();
        var limitDay   = now.getDate();
        var limitMonth = now.getMonth();
        var limitYear  = now.getYear() - 13;
        var limit = new Date(limitYear, limitMonth, limitDay);
        
        var guardianInfo = document.getElementById('guardian_info');
        var guardianName = document.getElementById('guardian_name');
        var guardianEmail = document.getElementById('guardian_email');
        var guardianRelationship = document.getElementById('guardian_relationship');
        
        if (Date.parse(born) <= Date.parse(limit)) {
            guardianInfo.style.display = 'none';
            guardianName.style.display = 'none';
            guardianEmail.style.display = 'none';
            guardianRelationship.style.display = 'none';
        }
        else {
            if (navigator.userAgent.indexOf('MSIE') != -1) {
                guardianInfo.style.display = 'block';
                guardianName.style.display = 'block';
                guardianEmail.style.display = 'block';
                guardianRelationship.style.display = 'block';
            }
            else {
                guardianInfo.style.display = 'table-row';
                guardianName.style.display = 'table-row';
                guardianEmail.style.display = 'table-row';
                guardianRelationship.style.display = 'table-row';
            }
        }

    }
}
function updateState(state) {
    var oSelect = document.getElementById('select_state');
    var oText = document.getElementById('text_state');
    if ((state == 'United States' || state == 'Canada')) {
        oSelect.style.display = 'block';
        oText.style.display = 'none';
        oText.name = 'disabled';
    }
    else {
        oSelect.style.display = 'none';
        oText.style.display = 'block';
        oText.name = 'state';
    }
}