.source-tooltip {
    display: none;
    position: absolute;
    padding: 5px;
    background: #fff;
    border: 1px solid #ccc;
    border-radius: 5px;
}
a.source:hover .source-tooltip {
    display: inline-block;
}
.source-favicon {
    width: 16px;
    vertical-align: middle;
    margin-right: 5px;
}