Sticky

snippet.js

    // Sticky Navigation
    var header = document.getElementById('header');
    var sticky = header.offsetTop;

    window.onscroll = function () {
        stickyNav()
    };

    function stickyNav() {
        if (window.pageYOffset > sticky) {
            header.classList.add('sticky');
        } else {
            header.classList.remove('sticky');
        }
    }