body {
  font-family: Arial, Helvetica, sans-serif;
  font-weight: bold;
  text-align: center;
}

#board {
  width: 400px;
  height: 400px;
  border: 10px solid darkgray;
  background-color: lightgray;

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

#board div {
  width: 48px;
  height: 48px;
  border: 1px solid whitesmoke;

  /* text */
  font-size: 30px;
  display: flex;
  justify-content: center;
  align-items: center;
}

.tile-clicked {
  background-color: darkgrey;
}

.x1 {
  color: blue;
}

.x2 {
  color: green;
}

.x3 {
  color: red;
}

.x4 {
  color: navy;
}

.x5 {
  color: brown;
}

.x6 {
  color: teal;
}

.x7 {
  color: black;
}

.x8 {
  color: gray;
}

#flag-button {
  width: 100px;
  height: 50px;
  font-size: 30px;
  background-color: lightgray;
  border: none;
}