body {
  /*background-image: url(images/bg.jpg);
  background-position: center center;
  background-repeat: no-repeat;
  background-attachment: fixed;
  background-size: cover;*/
  background-color:#ffffff;
}

.center-block {
  max-height: 90%;
  max-width: 90%;
  position: absolute;
  top: 0;
  bottom: 0;
  left: 0;
  right: 0;
  margin: auto;
  text-align: center;
  margin-top: auto;
}