body {
  background-color: #fffacd;
  font-family: sans-serif;
}
table {
  border-collapse: collapse;
  margin: 20px auto;
}
th, td {
  border: 1px solid #333;
  width: 180px;
  height: 80px;
  text-align: center;
}
th {
  background-color: #ddd;
}
td.diagonal {
    background-color: #ccc;
}