body {
  background-color: #333;
}

main {
  width: 600px;
  min-height: 500px;
  padding: 30px;
  margin: 30px auto;
  background-color: #111;
  color: #666;
  box-shadow: 0 0 10px 1px #666;
}

table {
  margin: 30px auto;
}

td {
  border: 3px solid #666;
  width: 100px;
  height: 100px;
  font-size: 3em;
  text-align: center;
  text-transform: uppercase;
}