style,

body {

  background-image: url("https://media.istockphoto.com/id/925115768/vector/abstract-red-background-christmas-background.jpg?s=612x612&w=0&k=20&c=UHrYa86N-MP5a6goyC1HvcWf-qOgwLjf_90DcNz9aOc=");
  background-repeat: repeat;

  background-size: cover;
}

style