html,
body {
  margin: 0;
  padding: 0;
  width: 100%;
  height: 100%;
  overflow: hidden;
}

.background-image {
  width: 100%;
  height: 100%;
  background-image: url("https://i.imgur.com/Qq9V0DG.jpeg");
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
  display: none;
}

.show {
  display: block;
}