AOC, body {
max-width: 500px;
margin: auto;
}
.post {
background: white;
color: black;
padding: 5px;
border: 1px solid gray;
}
.link {
display: block;
background: white;
color: black;
padding: 5px;
border: 1px solid gray;
}

Два дива? Пфф 0)