Ícones dos botões não funcionam e os botões também | CSS: dispondo elementos com Flexbox e Grid

HTML

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <title>HZC/Home</title>
    <link rel="stylesheet" href="reset.css">
    <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="estiloVS.css">
    <link rel="stylesheet" href="icones.ttf">
</head>
<body>
    <header class="cabecalho">
        <button class="cabecalho__menu" aria-label="Menu"><i></i></button>
        <img src="assets/img/logo.svg" alt="logotipo HZC" class="cabecalho__img">
        <button class="cabecalho__notificacao" aria-label="Notificação"><i></i></button>
    </header>
    <nav class="menu-lateral">
        <img src="assets/img/logo.svg" alt="logotipo HZC" class="menu-lateral__logo">
        <a href="#" class="menu-lateral__link menu-lateral__link-inicio menu-lateral__link-ativo">Início</a>
        <a href="#" class="menu-lateral__link menu-lateral__link-videos menu-lateral__link-ativo">Vídeos</a>
        <a href="#" class="menu-lateral__link menu-lateral__link-picos menu-lateral__link-ativo">Picos</a>
        <a href="#" class="menu-lateral__link menu-lateral__link-integrantes menu-lateral__link-ativo">Integrantes</a>
        <a href="#" class="menu-lateral__link menu-lateral__link-camisas menu-lateral__link-ativo">Camisas</a>
        <a href="#" class="menu-lateral__link menu-lateral__link-pinturas menu-lateral__link-ativo">Pinturas</a>
    </nav>
</body>
</html>

CSS

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

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

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

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

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

.menu-lateral {
    display: flex;
    flex-direction: column;
    background-color: #15191C;
    width: 75vw;
    height: 100vh;
    position: absolute;
    left: 0vh;
    transition: .25s;
}

.menu-lateral__logo {
    align-self: center;
    width: 118px;
    padding: 16px;
}

.menu-lateral__logo {
    align-self: center;
    width: 118px;
    padding: 16px;
}

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

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

.menu-lateral__link::before {
    content: "\e900";
    width: 24px;
    height: 24px;
    font-size: 24px;
    position: absolute;
    left: 24px;
}

.menu-lateral__link-inicios::before {
    content: "\e902";
}

.menu-lateral__link-videos::before {
    content: "\e90e"
}

.menu-lateral__link-picos::before {
    content: "\e909"
}

.menu-lateral__link-integrantes::before {
    content: "\e903"
}

.menu-lateral__link-camisas::before {
    content: "\e900"
}

.menu-lateral__link-pinturas::before {
    content: "\e90a"
}