title: Change label style when input has text
body: <p>I want to have my label hidden when the input hasn't been typed in because I have placeholder text but once it is typed in I want it to appear by changing the opacity. </p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-css lang-css prettyprint-override"><code>label {
    display: block;
    color:rgba(146,20,34,0);
    text-align: left;
    margin: 0;
    padding-left: 12.2%;
    font-size: 75%;
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;label for="name"&gt;Full Name&lt;/label&gt;
  &lt;input type="text" name="name" placeholder="Full Name" id="name" value=""&gt;
  &lt;br&gt;
  &lt;label for="customerNum"&gt;Customer Number&lt;/label&gt;
  &lt;input type="number" name="customerNum" placeholder="Customer Number" value=""&gt;</code></pre>
  </div>
  </div>
  </p>