const toggleIcons = document.getElementsByClassName("m-navbar__navheader--toggleIcon")[0];
const nav = document.getElementsByClassName("site-nav")[0];

function toggle(element) {
    if (nav.classList.contains("shown")) {
        nav.classList.remove("shown");
    } else {
        nav.classList.add("shown");
    }
}

toggleIcons.addEventListener("click", toggle);