<script>
function myFunction() {
var element = document.getElementById("header");
element.classList.toggle("header-open");
}
</script>
<script>
function myFunction() {
var element = document.getElementById("my333");
element.classList.toggle("navtop_open");
}
</script>
const btn1 = document.querySelector('.btn1');
btn1.addEventListener("click", myFunction);