title: How to customize wtforms' FileField as an image button?
body: <p>I'm trying to load an image from a project's folder to use as icon instead of the normal "choose file". Here's what I've tried so far. Not only the image isn't loaded, the old button is only displayed in half. </p>
  
  <p>HTML</p>
  
  <pre><code>&lt;div&gt;{{ form.tweet_image(class="submit-image-tweet")}}&lt;/div&gt;
  </code></pre>
  
  <p>CSS</p>
  
  <pre><code>.submit-image-tweet {
      background: url(../templates/images/camera_icon.png) no-repeat;
      cursor: pointer;
      border: none;
      width: 40px;
      height: 40px;
  }
  </code></pre>