querySelector
var circles = document.querySelectorAll('.circle');
circles.forEach(function(elem){
let items = elem.querySelectorAll('a');
for(var i = 0, l = items.length; i < l; i++) {
items[i].style.left = (50 - 35*Math.cos(-0.5 * Math.PI - 2*(1/l)*i*Math.PI)).toFixed(4) + "%";
items[i].style.top = (50 + 35*Math.sin(-0.5 * Math.PI - 2*(1/l)*i*Math.PI)).toFixed(4) + "%";
}
});
var buttons = document.querySelectorAll('.menu-button');
buttons.forEach(function(button){
button.addEventListener('click', function(e) {
e.preventDefault();
this.parentElement.querySelector('.circle').classList.toggle('open');
});
});