.container{
  width:600px;
}
.error{
  display: none;
  color:#FF0000;
  font-size: 10px;
}

.voitureClass{
  width:100px;
  height:50px;
  position: absolute;
  border: 3px solid black;
  text-align: center;
  line-height:50px;
  font-size: 30px;
}

#piste{
  width: 100%;
  height:600px;
  border:5px solid grey;
  position: relative;
}
#depart{
  height:600px;
  position: absolute;
  left:100px;
  border:2px dashed yellow;
}
#arrivee{
  height:600px;
  position: absolute;
  right:100px;
  border:2px dashed red;
}