body {
  text-align: center;
}
#board {
  height: 540px;
  width: 630px;

  background-color: blue;
  border: 10px solid navy;
  border-radius: 10px;

  margin: 0 auto;
  display: flex;
  flex-wrap: wrap;
}

.tile {
  height: 70px;
  width: 70px;
  background-color: white;
  border-radius: 50%;
  margin: 5px;
  border: 5px solid navy;
}
.red-piece {
  background-color: red;
}
.yellow-piece {
  background-color: yellow;
}