@keyframes spin {
  0% {
    transform: rotate(0deg);
  }
  100% {
    transform: rotate(2160deg);
  }
}
.playing {
  animation: 5s cubic-bezier(.4,.5,.5,1) 0s 1 normal none running spin;
}

#app {
  min-height: 80vh;
  margin: 2rem auto;
  padding: 2rem;
  border-radius: 16px;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.3);
  text-align: center;
}

button {
  padding: 1rem;
  font-size: 2rem;
  display: block;
  margin: 1rem auto;
}

input {
  text-align: center;
  background: none;
  border: none;
  border-bottom: 1px solid #999;
  width: 100%;
  font-size: 1.5rem;
  color: var(--fg-color);
  line-height: 3rem;
  padding: 0.5rem 0.5rem;
}
#input {
  padding: 2rem;
  min-height: 20rem;
  align-items: center;
}
#output {
  height: 40rem;
  font-size: 1.5rem;
}
#output>* {
  align-self: center;
}
li {
  list-style:none;
}
ul,ol {
  padding-left: 0;
}

#app h2 {
  font-size: 3rem;
  text-align: center;
  margin: 3rem 0;
}