File input is not properly rendered

[jantoniomartin]

I have a form with a file input and its file selection button is cut. I've tried changing it's properties in a custom css file, but I couldn't fix it.

This is how it looks like: https://www.dropbox.com/s/817f0jxvmjcgimh/file-input.png?dl=0

And this is the relevant html rendered by as_bootstrap filter:

<form enctype="multipart/form-data" action="" method="post" class="form-vertical">
  <div id="div_id_picture" class="form-group  ">
    <label for="id_picture" class="control-label  ">Picture</label>
    <div class="">
      <input class=" form-control" id="id_picture" name="picture" type="file" />
    </div>      
  </div>
</form>