img {
  display: block;
  width: 100%; }

html, body {
  height: 100%; 
  width: 100%;}

#bg-1, #bg-2, #bg-3, #bg-4{
  background-size: cover;
 
  background-color: #999; }

#bg-1 {
  background-image: url("../images/bb2.jpg"); 
  width: 100%;
  }

#bg-2 {
  background-image: url("../images/bb3.jpg"); 
  width: 100%;
  }
  
#bg-3 {
  background-image: url("../images/bb4.jpg"); 
  width: 100%;
  }
 
 #bg-4 {
  background-image: url("../images/bb5.jpg"); 
  width: 100%;
  }