<script>
(function($) {
    $(document).ready(function() {
        function setMenuPoistion(){
        var menuSection = $('.my_menu_section'),
            headerHeight = $('.my_header_section .et_pb_fullwidth_header').outerHeight();
        menuSection.css('top', headerHeight+18);
        }
        setMenuPoistion();
        $(window).resize(function(){
            setMenuPoistion();
        })

    });
})(jQuery);
</script>