[Dúvida] Desafio 1 | Praticando CSS: Grid e Flexbox | Alura

[Dúvida] Desafio 1

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="stylesheet" href="mecentraliza.css">
</head>

<body>
    <main class="centralizar">
        <div>
            <p>Me centraliza!</p>
        </div>
    </main>
</body>

CSS

main {
    height: 100vh;
    width: 100vw;
}


.centralizar {
     display: flex;
     justify-content: center;
      align-items: center;
}

div { 


    width: 240px;
    height: 110px;
    font-size: 36px;
    font-weight: bold;
    background-color: #fff;
    border-radius: 4px;
    padding: 0 10px;
    background-image: linear-gradient(315deg, #4dccc6 0%, #96e4df 74%);
    box-shadow: 4px 4px 6px 0 rgba(255, 255, 255, .3),
        -4px -4px 6px 0 rgba(116, 125, 136, .2),
        inset -4px -4px 6px 0 rgba(255, 255, 255, .2),
        inset 4px 4px 6px 0 rgba(0, 0, 0, .2);
 }