body {
  font-family: "Courier New", Courier, monospace;
}

.header {
  text-align: center;
  margin-block-end: 10px;
}

.col {
  border: 1px solid black;
  width: 10px;
  height: 10px;
}

.coloured {
  background-color: green;
}

.rows {
  display: flex;
  justify-content: center;
}