.stone {
  display: block;
  margin: 0;
  opacity: 0.1;
  padding: 0;
  text-align: center;
}

.stone--color--blue {
  background-color: #1f57ac;
}

.stone--color--gray {
  background-color: #ffffff;
}

.stone--color--green {
  background-color: #1fac65;
}

.stone--color--orange {
  background-color: #ac631f;
}

.stone--color--red {
  background-color: #ac281f;
}

.stone:hover {
  opacity: 0.5;
}

.stone--highlighted {
  border: 1px solid #ffffff;
}