function toggle()
    {
    document.getElementById('mytable').style.display='';
    }
    function toggle2()
    {
    document.getElementById('mytable').style.display='none';
    }
function ellenoriz()
{
valid = true;
    if ( document.contact_form.name.value == "" )
    {
        alert ( "Please provide your name." );
        valid = false;
    }
    if ( document.contact_form.email.value == "" )
    {
        alert ( "Please provide your e-mail address." );
        valid = false;
    }
    if ( document.contact_form.message.value == "" )
    {
        alert ( "Please provide the message text." );
        valid = false;
    }
    return valid;
}