body {
  background-image: url('space.jpg');
  background-size: cover;
  background-repeat: no-repeat;
  background-attachment: fixed;
  background-position: center;

  display: flex;              
  flex-direction: column;
  justify-content: center;
  align-items: center;
  
  margin: 0;
  min-height: 100vh;
}

h1 {
  color: white;
  text-align: center; 
}