function valid(form) {
  if (form.name.value=='') {
    alert("You must indicate your name.");
    form.name.style.backgroundColor='#F3DDD5';
    return false;
  }
  else { form.name.style.backgroundColor=''; } 
  
if (form.email.value=='') {
    alert("You must indicate the email.");
    form.email.style.backgroundColor='#F3DDD5';
    return false;
  }
  else { form.email.style.backgroundColor=''; }

if (form.message.value=='') {
    alert("You must indicate your message.");
    form.message.style.backgroundColor='#F3DDD5';
    return false;
  }
  else { form.message.style.backgroundColor=''; }


  return true;
}