<!-- Estilos privados -->
<style type="text/css">
    .top {
    border-top:thin solid;
    border-color:gray;
    }
    .bottom {
    border-bottom:thin solid;
    border-color:ray;
    }
    .left {
    border-left:thin solid;
    border-color:gray;
    }
    .right {
    border-right:thin solid;
    border-color:gray;
    }
</style>
<!-- Scripts privados -->
<script>
function goBack() {
    window.history.back()
}
</script>
