body {
  margin:0;
  background-color: black;
}

#fond{
  top:50%;left:50%;
    position:absolute;
    width:800px;height:600px;
    margin-left:-400px;
    margin-top:-300px;
    object-fit: scale-down;
    background-image: url(images/nuit_constellation950.png);
    background-position:center center;
    background-repeat: no-repeat;
    background-size: cover;  
}


.constellation {
  background-position:center center;
  background-repeat: no-repeat;
  background-size: cover;  
  position: absolute;
  top: 20px;
  left: 176px;
  width: 440px;
  height: 270px;
  cursor:pointer;
  display:none;
/*  border:solid 1px red;*/
}

#c01 {
    background-image: url(images/grandeourse_1000x559.png);
    z-index:300;
}

#c02 {
    background-image: url(images/petiteourse_1000x559.png);
  z-index:250;
  
}

#c03 {
    background-image: url(images/andromeda_1000x559.png);
  z-index:250;
  
}

#c04 {
    background-image: url(images/cassiopea_1000x559.png);
  z-index:250;
  
}

#c05 {
    background-image: url(images/orion_1000x559.png);
  z-index:250;
  
}