div.logo_sponsor{
   border: medium solid gray;
   box-shadow: 0 9px 13px #444;
   display: block;
   margin: 50px;
   float: left;
}
div.logo_sponsor:hover{
   border: medium solid gray;
   box-shadow:
   0px 2px 2px 0px rgba(0, 0, 0, 0.5) inset,
   0px 2px 2px 0px rgba(255, 255, 255, 0.5);
   display: block;
   margin: 50px;
}
.image_lien_sponsor {
    padding: 2px;
}