.ventana{
  background-color:grey;
  width:300px;
  padding: 10px 20px;
  margin: 20% auto;
  position: relative;
}
.modal{
  background-color: rgba(0,0,0,.8);
  position:fixed;
  top:-250px;
  right:0;
  bottom:0;
  left:0;
  opacity:0;
  pointer-events:none;
  transition: all 1s;
}
#IrVentanaFlotante:target{
  opacity:1;
  pointer-events:auto;
}
.opcion{/*width: 100px;
        background-color:yellow;
border:1px solid black;*/}