screen.css

html {
    font-family: 'Helvetica', sans-serif;
    font-size: 14px;
    color: black;
}

body {
    width: 600px;
    margin: 10px auto 10px auto;
}

div#header {
    font-size: 16px;
    font-weight: bold;
}

div#navigation {
    float: right;
}

div#navigation a {
    margin-left: 10px;
}

div#footer {
    text-align: center;
    font-style: italic;
    font-size: 11px;
    margin-top: 30px;
}

h1 {
    color: rgb(150, 150, 150);
    border-bottom: 2px solid rgb(150, 150, 150);
    font-size: 22px;
    margin-top: 30px;
}

li {
    list-style-type: square;
}

a {
    color: rgb(30, 30, 130);
    font-weight: bold;
    text-decoration: none;
}

div.figure {
    text-align: center;
}

div.figure p.caption {
    font-style: italic;
}