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var login = document.getElementById('log-in'); 
var front = document.querySelector('.user-front'); 
var back = document.querySelector('.user-login'); 
var humburger = document.getElementById('navigation__humburger'); 
 
 
 
// hamburgerMenu 
humburger.addEventListener('click', () => { 
    if (humburger.classList.contains('navigation__humburger_active')) { 
       humburger.classList.remove('navigation__humburger_active'); 
    } else { 
        humburger.classList.add('navigation__humburger_active'); 
 
    } 
}); 
 
//Log-in 
login.addEventListener('click',function () { 
    front.style.cssText='transform: rotateY(180deg) translate(50%,-50%); \ 
    backface-visibility: hidden; \ 
    transition: 1s; '; 
    back.style.cssText='transform: translate(-50%, -50%);  '; 
    login.style.display = 'none'; 
});