/*
* Hide class="elementid-permalink", except when an enclosing heading
* has the :hover property.
*/
.headerlink, .elementid-permalink {
    visibility: hidden;
}
h1:hover > .headerlink,
h2:hover > .headerlink,
h3:hover > .headerlink,
h4:hover > .headerlink,
h5:hover > .headerlink,
h6:hover > .headerlink,
dt:hover > .elementid-permalink {
    visibility: visible 
}