function contact_us(){
  var name = eval("document.getElementById('fullname')");
  var email = eval("document.getElementById('email')");
  var phone = eval("document.getElementById('phone')");
  if(name.value && email.value && phone.value){
    document.contact_us_form.submit();
  }else if(!name.value){
    alert("Please enter your Full Name.");
    name.style.backgroundColor = "#ffffcc";
  }else if(!email.value){
    alert("Please enter your E-mail Address.");
    email.style.backgroundColor = "#ffffcc";
  }else if(!phone.value){
    alert("Please enter your Phone Number.");
    phone.style.backgroundColor = "#ffffcc";
  }
}