una/template/menu_main_submenu.html

<ul id="bx-menu-main-submenu" class="bx-menu-main-submenu bx-menu-object-__object__ bx-clearfix">
    <li class="bx-menu-main-submenu-div bx-def-padding-sec-left bx-def-padding-sec-right"><i class="sys-icon angle-right bx-def-font-grayed"></i></li>
    <bx_repeat:menu_items>
        <li class="bx-def-padding-sec-right bx-def-padding-sec-left bx-def-color-bg-hl-hover __class_add__"><a href="__link__" target="__target__" onclick="__onclick__">__title__</a></li>
    </bx_repeat:menu_items>
</ul>
<script language="javascript">
    $(document).ready(function () {
        // add default class to active menu items
        $('.bx-menu-main-submenu > li.bx-menu-tab-active').not('.bx-def-color-bg-active').addClass('bx-def-color-bg-active');
    });
</script>