body{  
  width: 960px;
  margin: 10px auto;
  text-align: center}

div.cuerpo{
  width: 960px;
  float: left;
  text-align: left;
}

div.margen{
  width: 249px;
  margin-top: 14ex;
  float: left;
}

input.a{width: 3ex;}
.margen {text-align: left; padding-top: 3ex;}
.margen p, .margen form{ text-align: left; padding-left: 10px;}

li{
  text-align: left;
  list-style: none;
  padding: 3px 0 5px 0;
  border-bottom: 1px #333 dotted;}

dl {
text-align: left;
}
div.barrera{
  width: 100%;
  clear: both;
  }

form {
	padding: 2px;
	background: #fff;
	border: 1px solid gray;
}

form div#div_formu{
	background: #fff;
	padding: 10px;
	border: 1px solid gray;
	
}
	
div#datos_formulario{
	float: left;
	text-align: right;
	border-right: grey 1px solid;

}
div#envio{
	float: left;
	width: 50px;
	border: 1px dashed pink;
	margin: 20px;
	}