ul.backlinks
{
    list-style: none
}

ul.backlinks > li.unexplored::before
{
    content: '⊞';
    color: black;
    display: inline-block;
    width: 1em;
    margin-left: -1em
}

ul.backlinks > li::before
{
    content: "⊟";
    color: black;
    display: inline-block;
    width: 1em;
    margin-left: -1em
}