.bgb {

  /* Full height */
  height: 100%;

  /* Center and scale the image nicely */
  background-position: center;
  background-repeat: no-repeat;
  background-size: cover;
}

  @media only screen and (min-width: 768px) {    
    .bgb {
      /* The image used */
      background-image: url("/newface/img/webback.png");
    }
  }

  @media only screen and (max-width: 767px) {   
    .bgb {
      /* The image used */
      background-image: url("/newface/img/mobilback.png");
    }
  }