#nav {
    margin-bottom: 10px;
}
#nav > a {
    display: inline-block;
    padding: 10px;
    background-color: lightgrey;
    text-decoration: none;
    border-radius: 4px;
}

.hidden {
    display: none;
}
#message {
    background-color: lightblue;
    padding: 5px;
    margin-bottom: 5px;
}