.descending:after,
.ascending:after{
    content: ' ';
    position: relative;
    left: 5px;
    border: 7px solid transparent;
}
.descending:after{
    top: 10px;
    border-top-color: silver;
}
.ascending:after{
    bottom: 15px;
    border-bottom-color: silver;
}
.descending a,
.ascending a{
    color: inherit;
}