body {
  background-image: url('images/background-1920x1600.jpg');
  background-repeat: no-repeat;
  background-attachment: fixed;
  background-size: 100% 100%;
}

#caimg {
  width: 50%;
  margin: auto;
  position: absolute;
  top: 0; left: 0; bottom: 0; right: 0;

}