Aula 2 - Mais funcionalidades do Flexbox: Faça como eu fiz | CSS: dispondo elementos com Flexbox e Grid

Segue o código desenvolvido em aula: HTML:

<!DOCTYPE html>
<html lang="pt-br">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">

    <link rel="preconnect" href="https://fonts.googleapis.com">
    <link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>
    <link rel="stylesheet" href="https://fonts.googleapis.com/css2?family=Open+Sans:wght@400;600;700&display=swap">
    <link rel="stylesheet" href="assets/css/reset.css">
    <link rel="stylesheet" href="assets/css/styles.css">
    <title>HZC | Home</title>
</head>

<body>
    <header class="header">
        <button class="header__menu" aria-label="menu"><i></i></button>
        <img class="header__logo" src="assets/img/logo.svg" alt="Logotipo da HZC">
        <button class="header__noti" aria-label="notificação"><i></i></button>
    </header>
    <nav class="side-menu ">
        <img src="assets/img/logo.svg" alt="logotipo da HZC" class="side-logo">
        <a href="#" class="side-menu__link side-menu__link--inicio side-menu__link--ativo">Inicio</a>
        <a href="#" class="side-menu__link side-menu__link--videos">Videos</a>
        <a href="#" class="side-menu__link side-menu__link--picos">Picos</a>
        <a href="#" class="side-menu__link side-menu__link--integrantes">Integrantes</a>
        <a href="#" class="side-menu__link side-menu__link--camisas">Camisas</a>
        <a href="#" class="side-menu__link side-menu__link--pinturas">Pinturas</a>
    </nav>
    <script src="assets/js/index.js"></script>
</body>

</html>

CSS:

@font-face {
    font-family: 'icones';
    src: url(../font/icones.ttf);
}

body {
    background-color: #1D232A;
    font-family: 'Open Sans', 'icones', sans-serif;
    color: #FFFFFF;
}

.header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    background-color: #15191C;
    padding: 8px 16px;
    box-shadow: 0px 4px 4px rgba(0, 0, 0, 0.16);
}

.header__menu i::before {
    content: "\e904";
    font-size: 24px;
}

.header__logo {
    width: 40px;
}

.header__noti::before {
    content: "\e906";
    font-size: 24px;
}

.side-menu {
    display: flex;
    flex-direction: column;
    background-color: #15191C;
    width: 75vw;
    height: 100vh;
    position: absolute;
    left: -100vw;
    transition: .75s;
}

.side-menu--ativo {
    left: 0;
    transition: .75s;
}


.side-logo {
    width: 118px;
    padding: 16px;
    align-self: center;
}

.side-menu__link {
    height: 64px;
    color: #95999C;
    padding-left: 64px;
    display: flex;
    align-items: center;
}

.side-menu__link--ativo {
    color: #FFFFFF;
    padding-left: 56px;
    border-left: 8px solid #FFFFFF;
}

.side-menu__link::before {
    width: 24px;
    height: 24px;
    font-size: 24px;
    position: absolute;
    left: 24px;
}

.side-menu__link--inicio::before {
    content: "\e902";
}

.side-menu__link--videos::before {
    content: "\e90e";
}

.side-menu__link--picos::before {
    content: "\e909";
}

.side-menu__link--integrantes::before {
    content: "\e903";
}

.side-menu__link--camisas::before {
    content: "\e900";
}

.side-menu__link--pinturas::before {
    content: "\e90a";
}

JS:

const btn_menu = document.querySelector(".header__menu");
const menu = document.querySelector(".side-menu");

btn_menu.addEventListener('click', () => {
    menu.classList.toggle('side-menu--ativo');
});