input[type=checkbox].footnote-expander
{
    display: none;
}
input[type=checkbox].footnote-expander ~ span.footnote
{
    display: none;
}
input[type=checkbox].footnote-expander:checked ~ span.footnote
{
    display: inline;
    padding: 0;
}
input[type=checkbox].footnote-expander ~ label.footnote-expander > sup
{
    cursor: pointer;
}
input[type=checkbox].footnote-expander ~ label.footnote-expander > sup::after
{
    content: "[show]";
}
input[type=checkbox].footnote-expander:checked ~ label.footnote-expander > sup::after
{
    content: "[hide]";
}