// When the user scrolls the page, execute myFunction window.onscroll = function() {myFunction()}; // Get the header var header = document.getElementById("simple-banner"); // Get the offset position of the navbar var sticky = header.offsetTop; // Add the sticky class to the header when you reach its scroll position. Remove "sticky" when you leave the scroll position function myFunction() { if (window.pageYOffset > sticky) { header.classList.add("sticky"); } else { header.classList.remove("sticky"); } }