.down-app {
  top: 13.5rem;
}

.down-app .btn {
  width: 4.41rem;
  animation: a-loop 0.6s infinite linear;
  transform: scale(1.06);
}

.bar {
  position: fixed;
  max-width: 7.5rem;
}

.bar .btn {
  right: 0.2rem;
  top: 0.1rem;
  bottom: 0.1rem;
  width: 2.51rem;
}