.box {
  max-width: 1000px;
  margin-left: auto;
  margin-right: auto;
}

header, nav, main, footer {
  border: black 2px solid;
}

header {
  grid-row: 1/2;
  grid-column: 1/3;
}

nav {
  grid-row: 2/3;
  grid-column: 1/2;
}