body{
  background-image: url('../images/fbx/bg_freeboxos.svg');
  background-repeat: no-repeat;
  background-attachment: fixed;
  background-position: center;
  background-size: cover;
}
iframe{
  position: fixed;
  width: 100%;
  height: 100%;
  left: -2px;
  top: -2px;
  opacity: 0;
  transition : opacity 250ms;
}