.popup{
position:absolute;
top:190px;
width:800px;
height:420px;
left:50%;
margin-left:-400px;
filter:alpha(opacity=50); 
visibility:hidden;
z-index:1;
}

.boton_cerrar
 {
  width:450px;
  cursor:pointer;
  background-color:#003399;
  color:#FFFFFF;
  font-size:12px;
  border-bottom:0px;
  border-left:0px;
  border-right:0px;
  border-top:0px;
 }

.X{color:#FFFFFF;
font-size:16px;
font-family:"Arial Black";
margin-left:15px;
margin-right:5px;
}