function check_form() 
{
  validity = true; // assume valid 
  var error_txt ='';
  if (!check_empty(document.register_0.name.value))
  { 
      validity = false; 
      document.getElementById('name').className='formular_error'; error_txt ='Bitte tragen Sie Ihren <B>Namen</B> ein<br>'; } else {document.getElementById('name').className='formular';
  }
  if (!check_empty(document.register_0.vorname.value))
  { 
      validity = false; 
      document.getElementById('vorname').className='formular_error'; error_txt = error_txt +'Bitte tragen Sie Ihren <B>Vorname</B> ein<br>'; } else {document.getElementById('vorname').className='formular';
  }
  if (!check_empty(document.register_0.email.value))
  { 
      validity = false; 
      document.getElementById('email').className='formular_error'; error_txt = error_txt +'Bitte tragen Sie Ihre <B>Email-Adresse</B> ein<br><br>'; } else {document.getElementById('email').className='formular';
  }
  if(error_txt.length > 0){
    document.getElementById('error_txt').innerHTML = '<font color=#FF0000>'+ error_txt+'</font>';
    document.getElementById('error_tr').style.display='';
  } else {
    document.getElementById('error_tr').style.display='none';
  }
  return validity;
}

function check_empty(text) {
  return (text.length > 0); // gibt false zurück wenn leehr
}

function check_email(address) {
  if ((address == "")
    || (address.indexOf ('@') == -1)
    || (address.indexOf ('.') == -1))
      return false;
  return true;
}

function set_card(id){
    document.getElementById('div_1').style.display='none';
    document.getElementById('div_2').style.display='none';
    document.getElementById('div_3').style.display='none';
    document.getElementById('div_4').style.display='none';
    document.getElementById('div_5').style.display='none';
    document.getElementById('div_6').style.display='none';
    // pics setzen
    document.getElementById('pic_1').className='inaktiv';
    document.getElementById('pic_2').className='inaktiv';
    document.getElementById('pic_3').className='inaktiv';
    document.getElementById('pic_4').className='inaktiv';
    document.getElementById('pic_5').className='inaktiv';
    document.getElementById('pic_6').className='inaktiv';
    // tds setzen
    document.getElementById('td_1').className='td-inaktiv';
    document.getElementById('td_2').className='td-inaktiv';
    document.getElementById('td_3').className='td-inaktiv';
    document.getElementById('td_4').className='td-inaktiv';
    document.getElementById('td_5').className='td-inaktiv';
    document.getElementById('td_6').className='td-inaktiv';  
    // mouseout pics setzen
    document.getElementById('pic_1').onmouseout=new Function("this.className='inaktiv';document.getElementById('td_1').className='td-inaktiv';");
    document.getElementById('pic_2').onmouseout=new Function("this.className='inaktiv';document.getElementById('td_2').className='td-inaktiv';");
    document.getElementById('pic_3').onmouseout=new Function("this.className='inaktiv';document.getElementById('td_3').className='td-inaktiv';");
    document.getElementById('pic_4').onmouseout=new Function("this.className='inaktiv';document.getElementById('td_4').className='td-inaktiv';");
    document.getElementById('pic_5').onmouseout=new Function("this.className='inaktiv';document.getElementById('td_5').className='td-inaktiv';");
    document.getElementById('pic_6').onmouseout=new Function("this.className='inaktiv';document.getElementById('td_6').className='td-inaktiv';");
    // mouseout td setzen
    document.getElementById('td_1').onmouseout=new Function("this.className='td-inaktiv';document.getElementById('pic_1').className='inaktiv';");
    document.getElementById('td_2').onmouseout=new Function("this.className='td-inaktiv';document.getElementById('pic_2').className='inaktiv';");
    document.getElementById('td_3').onmouseout=new Function("this.className='td-inaktiv';document.getElementById('pic_3').className='inaktiv';");
    document.getElementById('td_4').onmouseout=new Function("this.className='td-inaktiv';document.getElementById('pic_4').className='inaktiv';");
    document.getElementById('td_5').onmouseout=new Function("this.className='td-inaktiv';document.getElementById('pic_5').className='inaktiv';");
    document.getElementById('td_6').onmouseout=new Function("this.className='td-inaktiv';document.getElementById('pic_6').className='inaktiv';");
    // aktiv schalten
    document.getElementById('pic_'+id).onmouseout=new Function("this.className='aktiv';document.getElementById('td_"+id+"').className='td-aktiv';");
    document.getElementById('td_'+id).onmouseout=new Function("this.className='td-aktiv';document.getElementById('pic_"+id+"').className='aktiv';");
    document.getElementById('div_'+id).style.display='';
    document.getElementById('pic_'+id).className='aktiv';
    document.getElementById('td_'+id).className='td-aktiv';
}