body {
    margin-left: 10%;
    margin-right: 10%
    }
p {
    text-align: justify
    }
h1, h2, h3, h4, h5, h6 {
    text-align: center
    }
pre {
    margin-top: 0;
    margin-bottom: 0
    }
hr {
    text-align: center;
    margin-left: 0%;
    margin-right: 20%;
    width: 50%
    }
hr.short {
    margin-right: 50%;
    margin-left: 10%;
    margin-top: 0;
    margin-bottom: 0;
    width: 40%
    }