html { 
  background: url(włos.jpg) no-repeat center center fixed; 
  -webkit-background-size: cover;
  -moz-background-size: cover;
  -o-background-size: cover;
  background-size: cover;
}

.szesnaście{
font-size: 20px;
margin-top: 37%;
margin-left:22% 
}