You have a weird doubling up of nav and ul elements that look like this;
<nav class="wrapper main-menu" role="navigation" itemscope="itemscope" itemtype="http://schema.org/SiteNavigationElement">
<ul id="menu-new-menu" class="menu">
<div class="no-print animated main-menu-container">
<nav class="wrapper main-menu" role="navigation" itemscope="itemscope" itemtype="http://schema.org/SiteNavigationElement">
<ul id="menu-new-menu" class="menu">
so the top and bottom border applied to ‘#menu-new-menu’ double-up too (there are 2 ul elements with id ‘#menu-new-menu’)