body, html {
  background: #111;
  color: white;
  font-family: sans-serif;
  text-align: center;
  text-transform: uppercase;
}
h1 {
  font-size: 40px;
}
#game {
  width: 100%;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
}
#keyboard {
  margin-top: 30px;
}
#keyboard > div {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 100%;
  margin: 0 auto 8px
}
.button {
  text-transform: uppercase;
  font-size: 16px;
  padding: 10px;
  margin: 3px;
  border-radius: 5px;
  height: 60px;
  border: none;
  cursor: pointer;
}
.button i {
  line-height: 35px;
  height: 60px;
}
.cell {
  width: 50px;
  height: 50px;
  line-height: 50px;
  border: 1px solid #939598;
  display: inline-block;
  margin: 3px;
  padding: 4px;
  font-size: 40px;
  font-weight: bold;
  perspective: 600px;
  transform-origin: 100% center;
}
.front, .back {
  transform-style: preserve-3d;
  backface-visibility: hidden;
  transition: transform .6s ease-in-out;
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
}
.front {
  z-index: 2;
  transform: rotateX(0deg);
}
.cell.flip .front {
  transform: rotateX(180deg);
}
.back {
  transform: rotateX(-180deg);
}
.cell.flip .back {
  transform: rotateX(0deg);
}
@keyframes letter-press {
  from {
    opacity: 0.5;
    transform: scale(0.9);
  }

  50% {
    opacity: 0.8;
    transform: scale(1.1);
  }

  to {
    opacity: 1;
    transform: scale(1);
  }
}
.run-letter-press-animation {
  animation: letter-press 300ms ease-out;
}
@keyframes word-not-valid {
  10%, 90% {
    transform: translate3d(-1px, 0, 0);
  }

  20%, 80% {
    transform: translate3d(2px, 0, 0);
  }

  30%, 50%, 70% {
    transform: translate3d(-4px, 0, 0);
  }

  40%, 60% {
    transform: translate3d(4px, 0, 0);
  }
}
.run-invalid-word-animation {
  animation: word-not-valid 0.8s cubic-bezier(.36,.07,.19,.97) both;
}
.alert {
  padding: 20px;
  background-color: #646464;
  color: white;
  display: inline-block;
  border-radius: 5px;
  position: absolute;
  top: 20px;
  left: 0;
  right: 0;
  margin-left: auto;
  margin-right: auto;
  width: 200px;
  font-weight: bold;
}