title: customising the look of f.file.field in rails
body: <pre><code>    &lt;div id="photo_attachment_container"&gt;
          &lt;%= f.file_field :photo %&gt;
      &lt;/div&gt;
  </code></pre>
  
  <p>Currently this just looks like a button, how can I add some css and customise the look (e.g dimensions background etc) of this button? Thanks</p>