style.css

* {
  padding: 0;
  margin: 0;
  font-family: Arial, Helvetica, sans-serif;
}

.score {
  position: absolute;
  left: 1rem;
  top: 1rem;
}

.score .victories {
  display: inline-block;
  width: 1rem;
  background-color: lightblue;
  border-radius: .5rem;
  text-align: center;
  margin-bottom: .5rem;
}

.game {
  display: flex;
  flex-direction: column;
  align-items: center;
}

.board {
  display: grid;
  width: 60vh;
  height: 60vh;
  margin: 1.5rem auto;
  grid-template-columns: 1fr 1fr 1fr;
  grid-template-rows: 1fr 1fr 1fr;
}

.tile {
  border: 0;
  width: 100%;
  height: 100%;
  font-size: 6vh;
  font-weight: bold;
  text-transform: uppercase;
  background-color: transparent;
  cursor: pointer;
}

.tile:hover {
  background-color: lightgray;
}

.tile:nth-child(1), .tile:nth-child(2),
.tile:nth-child(4), .tile:nth-child(5),
.tile:nth-child(7), .tile:nth-child(8) {
  border-right: 4px solid black;
}

.tile:nth-child(1), .tile:nth-child(2), .tile:nth-child(3),
.tile:nth-child(4), .tile:nth-child(5), .tile:nth-child(6) {
  border-bottom: 4px solid black;
}

.message {
  text-align: center;
}

.play-again {
  padding: .5rem 1rem;
}