Split a Drop-Down Into Multiple Columns In Shopify Debut Theme

I am Working On Vitakicks.com, As You Can See That The Dropdown on main navigation menu are way too long, some have 40 entries. Now i Want that If the number of items are more than 10, the column splits and makes another column. I Used some code as told by some developer at end of theme.liquid :

<script>
var maxRows = 6;
$('#menu > li.has-sub.level-1 > ul').each( function() {
var count = $(this).children().length;
var columns = Math.ceil(count/maxRows).toString();
$(this).css({
"-webkit-column-count": columns, 
"-moz-column-count": columns, 
"column-count": columns
 });
 });
 </script>

But This is not working On Debut Theme. So What is solution now? How can i do that?