index.js

'use strict';

const nav = document.querySelector('.mobile-nav');
const navMenuBtn = document.querySelector('.nav-menu-btn');
const navCloseBtn = document.querySelector('.nav-close-btn');

const navToggleFunc = function () { nav.classList.toggle('active'); }

navMenuBtn.addEventListener('click', navToggleFunc);
navCloseBtn.addEventListener('click', navToggleFunc);

const themeBtn = document.querySelectorAll('.theme-btn');


for (let i = 0; i < themeBtn.length; i++) {

  themeBtn[i].addEventListener('click', function () {

    document.body.classList.toggle('light-theme');
    document.body.classList.toggle('dark-theme');

    for (let i = 0; i < themeBtn.length; i++) {

      themeBtn[i].classList.toggle('light');
      themeBtn[i].classList.toggle('dark');

    }

  })

}