Bootstrap Tutorial - Create error alert block

The following code shows how to create error alert block.

Example

<!DOCTYPE html>
<html>
<head>
<script type='text/javascript'
  src='http://code.jquery.com/jquery-1.9.1.js'></script>
<link rel="stylesheet" type="text/css"
  href="http://netdna.bootstrapcdn.com/twitter-bootstrap/2.2.2/css/bootstrap-combined.min.css">
<script type='text/javascript'
  src="http://netdna.bootstrapcdn.com/twitter-bootstrap/2.2.2/js/bootstrap.min.js"></script>
<script type='text/javascript'>
$(window).load(function(){<!-- w w w .ja  v  a2 s  . com-->
    if (!navigator.mozGetUserMedia) {
        $("#gum").show();
    }
});
</script>
</head>
<body style='margin:30px'>
  <div id="gum" class="hide">
    <div class="alert alert-block alert-error fade in">
      <button type="button" class="close" data-dismiss="alert">&times</button>
      <h4 class="alert-heading">User Data is missing</h4>
      <p>
        Do you have the latest<a href="">Nightly</a>
        and set <i>media.navigator.enabled</i> to true?
      </p>
    </div>
  </div>
</body>
</html>

Click to view the demo