body {
    background-color: #000000;
    color: #ffffff;
    font-family: sans-serif;
}

a:link {
    color: #00ff00;
}
a:visited {
    color: #007700;
}
a:hover {
    color: #ff0000;
}

.topnav {
    background-color: #333;
    overflow: hidden;
}
.topnav a {
    float: left;
    color: #f2f2f2;
    text-align: center;
    padding: 14px 16px;
    text-decoration: none;
    font-size: 17px;
}
.topnav a:hover {
    background-color: #ddd;
    color:  black;
}
.topnav a.active {
    background-color: #000077;
    color: white;
}