.box {
    margin-left: auto;
    margin-right: auto;
    display: grid;
    grid-gap: 30px;
    padding-right: 100px;
}
body
{
    background-image: url('images/hubble.jpg');
    background-repeat: no-repeat;
    background-attachment: fixed;
    background-size: cover;
}
body{
    color: aliceblue;
    font-family: 'Courier New', Courier, monospace;
}

header{
    width: 100%;
    text-align: center;
    grid-row: 1 / 2;
    grid-column: 1 / 3;
}
nav{
    grid-row: 2 / 3;
    grid-column: 1 / 2;
    max-width: 150px;
}
main{
    grid-row: 2 / 3;
    grid-column: 2 / 3;
}
footer{
    grid-row: 3 / 4;
    grid-column: 1 / 3;
}