body {
  
  background: url(https://www.lsitools.com/wp-content/uploads/2017/04/iStock_000040926806_Double-1500x1000.jpg) no-repeat center center fixed; 
  -webkit-background-size: cover;
  -moz-background-size: cover;
  -o-background-size: cover;
  background-size: cover;
            
            }