body {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    text-align: center;
    margin: 0;
    padding: 0;
    width: 100%;
    min-height: 100vh;
    font-family: Arial, sans-serif;
}
main {
    max-width: 800px;
    width: 100%;
    padding: 20px;
}
nav ul {
    display: flex;
    justify-content: center;
    padding: 0;
    list-style: none;
}
nav ul li {
    margin: 0 15px;
}