body {
  margin: 0px;
  position: relative;
}

img {
  position: absolute;
  left: 0;
  top: 0;
  width: 100%;
  height: auto;
}

@media only screen and(max-width: 500px) {
  .desktop {
    display: none;
  }
}

@media only screen and(min-width: 501px) {
  .mobile {
    display: none;
  }
}