function setVisibility() {
    var iw = 0;

    if (window.innerWidth != undefined) { iw = window.innerWidth; }
    else { iw = document.documentElement.clientWidth}

    if (iw < 1300) {
        $('#contact').addClass('contact-hidden');
    }
    else {
        $('#contact').removeClass('contact-hidden');
    }
}

$(document).ready(function () { setVisibility() });
$(window).resize(function () { setVisibility() });