title: Token not generated on submit of card details
body: <p>I have mounted the card element but still on submit click i don't get the stripe token generated instead it shows the following error:</p>
  
  <p>Uncaught (in promise) Error: We could not retrieve data from the specified Element.
                Please make sure the Element you are attempting to use is still mounted.</p>
  
  <pre><code>&lt;span class="input input--filled" id="fullcard"&gt; 
      &lt;span id="card-element" class="input_field"&gt;&lt;/span&gt;  
       &lt;label class="input_label"&gt; 
        &lt;span class="input__label-content"&gt;Card details&lt;/span&gt; 
       &lt;/label&gt; 
  &lt;/span&gt;
  </code></pre>