Custom tubmlr 404 page

tumblr_custom_404

<script type="text/javascript" src="https://www.google.com/jsapi"></script>
<script type="text/javascript">
    google.load("jquery", "1.7.1");
</script>

<script type="text/javascript">
  $(document).ready(function() {
    var text_posts = $('.post-type-text')
    var not_found_title = $('.post-type-text').find('.post-content').children('h3').text()
    if(text_posts.length == 1 && not_found_title == "Not Found"){
      $('.post-type-text').find('.post-content').children('p').text('This is a test to customize 404');
    }
  });
</script>