function setFN() {
document.getElementById("fN").style.color="black";
document.getElementById("fNH").style.visibility="hidden";
}
function setSN() {
document.getElementById("sN").style.color="black";
document.getElementById("sNH").style.visibility="hidden";
}
function setWS() {
document.getElementById("wS").style.color="black";
document.getElementById("wSH").style.visibility="hidden";
}
function setAD() {
document.getElementById("aD").style.color="black";
document.getElementById("aDH").style.visibility="hidden";
}
function setCT() {
document.getElementById("cT").style.color="black";
document.getElementById("cTH").style.visibility="hidden";
}
function setML() {
document.getElementById("mL").style.color="black";
document.getElementById("mLH").style.visibility="hidden";
}
function setTP() {
document.getElementById("tP").style.color="black";
document.getElementById("tPH").style.visibility="hidden";
}


function validate_mailform() {
validity = true;

if (document.forms[0].firstName.value == "") 
{
document.getElementById("fN").style.color="red";
document.getElementById("fNH").style.visibility="visible";
document.forms[0].firstName.focus();
return false;
}

if (document.forms[0].surname.value == "") 
{
document.getElementById("sN").style.color="red";
document.getElementById("sNH").style.visibility="visible";
document.forms[0].surname.focus();
return false;
}
if (document.forms[0].affiliate.value == "") 
{
document.getElementById("wS").style.color="red";
document.getElementById("wSH").style.visibility="visible";
document.forms[0].affiliate.focus();
return false;
}
 if (document.forms[0].address.value == "") 
 {
document.getElementById("aD").style.color="red";
document.getElementById("aDH").style.visibility="visible"; 
document.forms[0].address.focus();
  return false;
  }
 if (document.forms[0].city.value == "") 
 {
document.getElementById("cT").style.color="red";
document.getElementById("cTH").style.visibility="visible";  
document.forms[0].city.focus();
  return false;
  }
if (document.forms[0].email.value == "") 
{
document.getElementById("mL").style.color="red";
document.getElementById("mLH").style.visibility="visible";
document.forms[0].email.focus();
return false; 
}
// Return false if e-mail field does not contain a '@' and '.' .
if (document.forms[0].email.value.indexOf ('@',0) == -1 || 
document.forms[0].email.value.indexOf ('.',0) == -1)
{
alert("please, insert a valid email address")
document.forms[0].email.select();
document.forms[0].email.focus();
return false;
}
if (document.forms[0].telephone.value == "") 
{
document.getElementById("tP").style.color="red";
document.getElementById("tPH").style.visibility="visible";
document.forms[0].telephone.focus();
return false;
}
if (validity)
return validity;
}