[DúvidaLista de exercícios | HTML e CSS: cabeçalho, footer e variáveis CSS

<!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">
    <title>Portifolio</title>
    <link rel="stylesheet" href="style.css">
</head>
<body>
    <header></header>
    <main class="apresentacao">
        <section class="apresentacao__conteudo">
            <h1 class="apresentacao__conteudo__titulo">Eleve seu negócio digital a outro nível <strong>com um Front-end de qualidade!</strong></h1>
            <p class="apresentacao__conteudo__texto">Olá, Bem-vindos ao site!</p>  
            <div class="apresentacao__links">
                <h2 class="apresentacao__links__subtitulo">Acesse minhas redes:</h2>
                <a class="apresentacao__links__link" href="https://instagram.com">Instagram</a>
                <a class="apresentacao__links__link" href="https://github.com">Github</a>
            </div>
        </section>
        <img src="./assets/html.png" alt="">
        
        //--------------------------------------------------CSS
        
        @import url('https://fonts.googleapis.com/css2?family=Krona+One&family=Montserrat:wght@400;600&display=swap');

* {
    margin: 0;
    padding: 0;
}

body{
    height: 100vh;
    box-sizing: border-box;
    background-color: #000000;
    color: #F6F6F6;
}

strong{
    color: #22D4FD;
}

.apresentacao {
    margin: 10% 15%;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.apresentacao__conteudo {
    width: 615px;
    display: flex;
    flex-direction: column;
    gap: 40px;
}

.apresentacao__conteudo__titulo {
    font-size: 36px;
    font-family: "Krona One", sans-serif;
}

.apresentacao__conteudo__texto {
    font-size: 24px;
    font-family: "Montserrat", sans-serif;
}

.apresentacao__links {
    display: flex;
    justify-content: space-between;
    flex-direction: column;
    align-items: center;
    gap: 32px;
}

.apresentacao__links__subtitulo {
    font-family: "Krona One", sans-serif;
    font-size: 25px;
    font-weight: 400;
}

.apresentacao__links__link {
    /* background-color: #22D4FD; */
    border: 2px solid #22D4FD;
    width: 280px;
    text-align: center;
    border-radius: 16px;
    font-size: 24;
    font-weight: 600;
    padding: 21.5px 0;
    text-decoration: none;
    color: #F6F6F6;
    font-family: "Montserrat", "sans-serif";
}


/*/
.apresentacao__links a {
    padding: 10px 20px;
    font-size: 18px;
    margin: 5px;
    color: white;
    background-color: #518ad4;
    border-radius: 5px;
}
/*/

    </main>
    <footer></footer>
</body>
</html>