.memory > .card {
  font-size: 2em;
  flex: 1 1 calc(100% / 6 - 0.4em);
  outline: 0.08em solid silver;
  margin: 0.2em;
  display: flex;
  cursor: default;
}

.memory > .card.hidden {
  background: silver;
}

.memory > .card.justMatched,
.memory > .card.justMismatched {
  outline: 0.1em solid green;
}
.memory > .card.justMismatched {
  outline-color: red;
}

.memory > .card.visible {
  cursor: not-allowed;
}

.memory > .card > .symbol {
  margin: auto;
}