html, body {
  height: 100%;
  margin: 0;
  padding: 0;
}
body {
  background-color: #b1bce1;
  background-image: url('img/bg.jpg');
  background-repeat: no-repeat;
  background-attachment: fixed; 
  background-size: 100% 100%;
}

.image-wrapper {
  padding-top: 50px;
  padding-bottom: 50px;
}

.image-wrapper > img {
  display: block;
  height: 100px;
  margin: 0 auto;
}