body {
  margin: 0;
  height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  background: silver;
  overflow: hidden;
}

.app {
  width: 300px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: space-between;
  user-select: none;
  position: relative;
}

h1 {
  margin: 0;
  color: sienna;
}

.game {
  transition: 0.3s;
}

.game.stop {
  filter: blur(10px);
}

.game .message {
  width: inherit;
  display: flex;
  justify-content: space-between;
  font-size: 1.2em;
  font-family: sans-serif;
}

.game .message span {
  font-weight: bold;
}

.game .digits {
  box-sizing: border-box;
  width: 300px;
  height: 300px;
  padding: 10px;
  border: 10px solid sienna;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  grid-gap: 10px;
}

.game .digits span {
  box-sizing: border-box;
  width: 80px;
  height: 80px;
  background-color: blanchedalmond;
  font-size: 30px;
  font-family: sans-serif;
  text-align: center;
  line-height: 2.5em;
  color: sienna;
  position: relative;
}

.game .digits span.wrong {
  border: 2px solid crimson;
}

.game .digits span.correct {
  background-color: chocolate;
  color: gold;
}

.select-level,
.game-over {
  box-sizing: border-box;
  width: 240px;
  height: 240px;
  border: 10px solid rgba(160, 82, 45, 0.8);
  border-radius: 50%;
  box-shadow: 
      0 0 0 0.3em rgba(255, 235, 205, 0.8),
      0 0 1em 0.5em rgba(160, 82, 45, 0.8);
  display: flex;
  flex-direction: column;
  align-items: center;
  font-family: sans-serif;
  position: absolute;
  bottom: 40px;
  visibility: hidden;
  z-index: 2;
}

.select-level .levels {
  margin-top: 60px;
  width: 190px;
  display: flex;
  justify-content: space-between;
  position: relative;
}

.select-level input[type=radio] {
  position: absolute;
  visibility: hidden;
}

.select-level label {
  width: 56px;
  height: 56px;
  background-color: rgba(160, 82, 45, 0.8);
  border-radius: 50%;
  color: blanchedalmond;
  text-align: center;
  line-height: 56px;
  cursor: pointer;
}

.select-level input[type=radio]:checked + label {
  background-color: sienna;
}

.select-level .play,
.game-over .again {
  width: 120px;
  height: 30px;
  background-color: sienna;
  color: blanchedalmond;
  text-align: center;
  line-height: 30px;
  border-radius: 30px;
  text-transform: uppercase;
  cursor: pointer;
}

.select-level .play {
  margin-top: 30px;
  font-size: 20px;
  letter-spacing: 2px;
}

.select-level .play:hover,
.game-over .again:hover {
  background-color: saddlebrown;
}

.select-level .play:active,
.game-over .again:active {
  transform: translate(2px, 2px);
}

.game-over h2 {
  margin-top: 40px;
  color: sienna;
}

.game-over p {
  margin: 3px;
  font-size: 20px;
  color: sienna;
}

.game-over .again {
  margin-top: 10px;
}