A simple way to handle multilevel menu on difference devices. This plugin convert multilevel menu into select menu.
This plugin support all browsers, as well as some old ones such as IE6/7/8.
Include below scripts in your page.
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script>
<script type="text/javascript" src="js/custom.js"></script>
$("#menu").respomenu({
select : $("select#devi-menu")
});