body {
    margin-left: 15%;
    margin-right: 15%;
    background-color: white
    }
img {
    border: 0
    }
h1, h2, h3 {
    text-align: center
    }
a:link {
    color: blue;
    text-decoration: none
    }
link {
    color: blue;
    text-decoration: none
    }
a:visited {
    color: blue;
    text-decoration: none
    }
a:hover {
    color: red
    }
.ind {
    margin-left: 10%;
    margin-right: 10%
    }
hr {
    text-align: center;
    width: 50%
    }
.ctr {
    text-align: center
    }
pre {
    font-family: Courier, monospaced
    }