body {
  background: #1f2f3e;
  color: white;
}

pre.title {
  text-align: center;
  margin: auto;
  font-size: 20px;
}

.explain {
  display: none;
}

button {
  cursor: pointer;
  text-align: center;
  padding: 12px;
  font-size: 16px;
  color: white;
  background: rgb(9, 0, 139);
  outline: none;
  font-family: monospace;
  border: none;
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}

.center {
  text-align: center;
  margin: auto;
}