.tablesort {
  display: inline-block;
  width: 16px;
  height: 16px;
  background-size: 100%;
}
.tablesort--asc {
  background-image: url(https://imgsvr.edgereg.net/ERImg/04/33/63/twistie-down.svg);
}
.tablesort--desc {
  background-image: url(https://imgsvr.edgereg.net/ERImg/04/33/63/twistie-up.svg);
}