.sortable-table th {
    cursor: pointer;
    background: #f4f4f4;
    transition: background 0.2s;
}
.sortable-table th:hover {
    background: #e0e0e0;
}
.sortable-table th:after {
    content: " ⇅";
    font-size: 0.8em;
    color: #888;
}