nav {
    background: rgba(255, 255, 255, 0.2);
    width: 3em;
    line-height: 3em;
}
nav li {
    padding-left: 1em;
    padding-right: 1em;
}
nav span {
    display: none;
    opacity: 0.7;
}
nav:hover {
    width: 8em;
}
nav:hover span {
    display: inline;
}