anchor.diff:      </div>
       <div class="span9">
         <div class="well">
  -        <input type="text" size="2" class="card-expiry-month" placeholder="02 (Month)" />
  +        <input type="text" size="2" class="card-expiry-month" placeholder="02 (Month)" required="required" />
           <span> / </span>
  -        <input type="text" size="4" class="card-expiry-year" placeholder="2013 (Year)" />
  +        <input type="text" size="4" class="card-expiry-year" placeholder="2013 (Year)" required="required" />
         </div>
       </div>
     </div>
  
positive.code:     </div>
      <div class="span9">
        <div class="well">
          <input type="text" size="20" id="card-cvc" autocomplete="off" class="card-cvc" placeholder="123 (3 or 4 digits)" />
        </div>
      </div>
    </div>
  
negative.code:     </div>
      <div class="span9">
        <div class="well">
          <input type="text" size="20" id="card-number" autocomplete="off" class="card-number" placeholder="4242********4242" required="required" />
        </div>
      </div>
    </div>
  