Jquery is required
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script>
To use this birthday picker:
<select id="year"></select>
<select id="month"></select>
<select id="date"></select>
<script>
PopulateBirthdayPicker("year", "month", "date");
</script>
Free to apply any css style on it!