header {
  color: white;
  font-family: "Helvetica Neue", sans-serif;
  font-size: 120px;
  font-weight: lighter;
  text-align: center;
  transition-duration: 5s;
}

h1 {
  color: white;
  font-family: "Helvetica Neue", sans-serif;
  font-size: 18px;
  font-weight: lighter;
  text-align: center;
  transition-duration: 1s;
}

body {
  background: linear-gradient(#464770, #477046, #967C89);
  background-size: 2000px 2000px;
  padding-top: 0 !important;
  text-align: center;
  transition-duration: 1s;
}

h2 {
  display: block;
  font-family: "Helvetica Neue", sans-serif;
  font-size: 20px;
  font-weight: lighter;
  text-align: center;
  padding: auto;
  transition-duration: 1s;
  color: white;
}

.c {
  border-radius: 50px;
  border-width: 2px;
  display: inline-block;
  margin: 8px;
  max-width: 100px;
  padding: 50px 40px;
  transition-duration: 1s;
  width: 100%;
}

.b {
  margin: 8px;
  border-radius: 50px;
  border-width: 2px;
  max-width: 100px;
  padding: 50px 40px;
  transition-duration: 0.5s;
  width: 100%;
  display: inline-block;
  cursor: pointer;
  opacity: 0.5;
  border: 2px solid #477046;
}

.start-btn {
  background-color: rgba(38, 38, 38, 0.32);
  color: white;
  padding: 20px;
  margin: 30px auto;
  display: block;
  cursor: pointer;
}

.start-btn:hover {
  background-color: white;
  color: black;
}

.b0 {
  background-color: #4CD964;
  color: rgba(255, 255, 255, 0.67);
  display: inline-block;
}

.b0:hover {
  background-color: rgba(14, 138, 14, 0.24);
  color: rgba(30, 91, 30, 0.84);
}

.b1 {
  background-color: #FF3B30;
  color: rgba(255, 255, 255, 0.67);
  display: inline-block;
}

.b1:hover {
  background-color: rgba(138, 14, 14, 0.24);
  color: rgba(91, 30, 30, 0.84);
}

.b2 {
  background-color: #007AFF;
  color: rgba(255, 255, 255, 0.67);
  display: inline-block;
}

.b2:hover {
  background-color: rgba(14, 76, 138, 0.24);
  color: rgba(30, 61, 91, 0.84);
}

.b3 {
  background-color: #FFCD00;
  color: rgba(255, 255, 255, 0.67);
  display: inline-block;
}

.b3:hover {
  background-color: rgba(138, 138, 14, 0.24);
  color: rgba(91, 91, 30, 0.84);
}

h4 {
  font-weight: lighter;
  font-family: "Helvetica Neue", sans-serif;
  font-size: 20px;
  display: block;
  text-align: center;
  color: white;
  padding: 60px;
}

footer {
  font-weight: lighter;
  font-family: "Helvetica Neue", sans-serif;
  font-size: 16px;
  display: block;
  text-align: center;
  padding: auto;
  color: rgba(76, 76, 76, 0.6);
  position: static;
}

footer:hover {
  color: white;
  transition-duration: 2s;
}

.selected {
  border: 2px solid white;
  opacity: 1;
}

.high-score {
  margin-left: auto;
  margin-right: auto;
  left: 0;
  right: 0;
  line-height: 240%;
}

.score {
  margin-left: auto;
  margin-right: auto;
  left: 0;
  right: 0;
}

.game-over {
  opacity: 1;
  animation: fadein 2s linear 1;
  animation-fill-mode: forwards;
  color: #FF3B30;
  position: absolute;
  margin-left: auto;
  margin-right: auto;
  left: 0;
  right: 0;
}

@keyframes fadein {
  0% {
    opacity: 0;
  }
  50% {
    opacity: 0.5;
  }
  100% {
    opacity: 1;
  }
}

.correct {
  display: none;
  animation: fadein 2s;
  position: absolute;
  margin-left: auto;
  margin-right: auto;
  left: 0;
  right: 0;
  opacity: 1;
  animation: fadeinout 1.7s linear 1 forwards;
  animation-fill-mode: forwards;
  color: #4CD964;
}

@keyframes fadeinout {
  0% {
    opacity: 0;
  }
  50% {
    opacity: 1;
  }
  100% {
    opacity: 0;
  }
}

.spacer {
  height: 50px;
}