+<th><a href="?sort_by={% if sort_by == "steps" %}-{% endif %}steps">steps</a></th>
+<th><a href="?sort_by={% if sort_by == "owners" %}-{% endif %}owners">owners</a></th>
+<th><a href="?sort_by={% if sort_by == "effort" %}-{% endif %}effort">effort</a></th>
+<th><a href="?sort_by={% if sort_by == "title" %}-{% endif %}title">title</a></th>