body {
  background-color: #000;
  margin: 0;
}

#bg,
#tip {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);

  width: 100%;
  height: auto;
  max-height: 100%;
  object-fit: contain;

  transition: opacity 1s;
  opacity: 0;
}

#tip {
  z-index: 1;
  color: #aaa;
  text-align: center;
}

#aplayer {
  margin: 0;
  position: fixed;
  bottom: 0;
  right: 0;
  z-index: 999;
  opacity: 0.8;
  transition: opacity 1s;
}

@media screen and (max-width: 768px) and (orientation: portrait) {
  #bg,
  #tip {
    transform: translate(-50%, -50%) rotate(90deg);
    width: 100vh !important;
    max-height: 100vw !important;
  }

  #aplayer {
    transform: rotate(90deg);
    right: unset;
    left: 0;
  }
}