body {
  margin: 0;
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;

  background: url("https://i.pinimg.com/736x/54/0b/58/540b584c79f0f6e73c9694307294a8d6.jpg") repeat-x center center;
  background-size: auto 100%;
}

.center-img {
  width: 600px;   
  max-width: none; 
}