body {
    margin-left: 20%;
    margin-right: 20%;
    text-align: justify
    }
h1, h2, h3, h5, h6 {
    color: green;
    text-align: center
    }
h4 {
    color: black;
    text-align: center
    }
.centclass {
    text-align: center
    }
p.ch {
    margin-bottom: 4em;
    margin-top: 4em;
    line-height: 1.5
    }
p.chsum {
    font-size: smaller;
    text-align: center;
    margin-bottom: 4em;
    margin-top: 4em;
    line-height: 1.1
    }