body {
    margin-left: 10%;
    margin-right: 10%
    }
.pn {
    text-indent: 0;
    font-size: smaller;
    text-align: right;
    color: silver
    }
#corpo p {
    text-align: justify;
    text-indent: 1em
    }
h1, h2, h3, h4 {
    text-align: center;
    margin-top: 3em;
    margin-bottom: 2em
    }