body {
  font-family: sans-serif;
  font-size: 100%;
  background-color: #fff;
}

img {
  position: absolute;
  max-width: 80%;
}
img:empty {
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}
@media screen and (orientation: portrait) {
  img {
    max-width: 90%;
  }
}
@media screen and (orientation: landscape) {
  img {
    max-height: 90%;
  }
}