I've set up a simple jQueryUI progressbar:

<script type="text/javascript">
            $(function() {
                    $("#progressbar").progressbar({
                            value: 35
                    });
            });
            </script>
<div id="progressbar">  </div>

Now, I'd like to color the of the bar based on it's value (e.g. <10 red, <50 yellow, >50 green). How do I do this?

Note: There are similar questions, but the answers were not clear enough to help me get things done. Hopefully, someone can point out an easier way or provide more detailed instructions. Thanks.