DoNiFF

const ADMIN_PASSWORD = '777';
let message;

let modal = prompt('Введите пароль');

if (modal === ADMIN_PASSWORD) {
  message = alert('Добро пожаловать!');
} else if (modal !== ADMIN_PASSWORD) {
  message = alert('Доступ запрещен, неверный пароль!');
} else if (modal === null || modal === "") {
  message = alert('Отменено пользователем!');
}

let blockTitles = document.querySelectorAll(".block-title");
let progresses = document.querySelectorAll(".progress");

blockTitles.forEach(function(item){
    item.addEventListener("click", function() {
          blockTitles.forEach(function(e) {
                if(e.classList[1] == "_active")
                {
                    e.classList.remove("_active");
                }
            })
            progresses.forEach(function(e) {
                if(e.classList[1] == "_active")
                {
                    e.classList.remove("_active");
                }
            })
            let attr = item.getAttribute("data-id");
            progresses.forEach(function(e) {
                if(e.getAttribute("data-id") == attr)
                {
                e.classList.add("_active");
                }
            })
            item.classList.add("_active");
        })
        })

document.getElementsByClassName('training__thanks').style.display = 'flex';

document.querySelector('training__thanks').style.display = 'flex';

<div class="projects-list back link3" onclick="opennewtab('site.com/'>