html, body {
  min-height: 100vh;
}
body {
  background-color: #f00;
  background-image: url(https://www.pinclipart.com/picdir/big/519-5192289_fire-clipart.png);
  background-repeat: no-repeat;
  background-position: center center;
  background-size: contain;
}

External CSS

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External JavaScript

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