To center the arrow, you can add this:
ul ul:after { margin-left: -20px; }
To fix the drop-down menu is not left, give a sufficient bottom addition as follows:
nav > ul > li > a { padding-bottom: 50px; }
Updated: drop-down menu and arrow:
Demo http://jsfiddle.net/esjrhg5n/
$(document).ready(function() { $("nav > ul > li").mouseover(function() { var the_width = $(this).find("a").width(); var child_width = $(this).find("ul").width(); var width = parseInt((child_width - the_width)/2); $(this).find("ul").css('left', -width); }); });
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