body {
  background-color: lightslategray;
}

nav {
  margin-bottom: 2vw;
}

#nav-title {
  font-size: 4vw;
  color: white;
}

#reset-button {
  margin-bottom: 3vw;
}

#difficulty-buttons {
  margin-bottom: 3vw;
}

.hidden {
  display: none;
}

.btn {
  margin-right: 2vw;
  font-size: 3vw;
}

#message {
  margin-bottom: 2vw;
  font-size: 5vw;
}

#play-area {
  display: grid;
  justify-items: center;
  grid-template-columns: repeat(5, 1fr);
}

.card.large {
  font-size: 4vw; 
}