Add smooth scroll to all anchors links

Just use the following js:

//Smooth scroll for anchors
    $('a[href*="#"]:not([href="#"])').click(function() {
    var offset = -20; // <-- change the value here
    if (location.pathname.replace(/^\//,'') == this.pathname.replace(/^\//,'') && location.hostname == this.hostname) {
        var target = $(this.hash);
        target = target.length ? target : $('[name=' + this.hash.slice(1) +']');
        if (target.length) {
            $('html, body').animate({
                scrollTop: target.offset().top + offset
            }, 500);
            return false;
        }
    }
});