span {
  position:absolute;
  display: inline-block;
  width:800px;
  height:2px;/*100*/
  left:calc(50% - 400px);
  top: calc(50% - 1px);
  color:rgba(255,255,255,0.65);
  text-shadow: 0 0 2px rgba(0,0,0,0.25);
  font-size:32px;
  font-weight: bold;
  text-align: center;
  line-height: 2px;
  cursor:default;
  opacity:0;
  transition: 10s;
}
span.actif {
  opacity:1;
}