body{
  background-color:black;
  background-image:url("SAO.png");
  background-attachment:fixed;
  background-size:contain;
  height:100%;
  width:100%;
}
.bcdwhite{
  position:relative;
  top:-100px;
  padding-top:50%;
  margin:auto;
  max-height:200px;
  width:200px;
  background-color:white;
  opacity:1
}
/* Obtenir valeur exactes pixels pour les padding/margin*{
  box-sizing:border-box;
}*/