상품목록에서 탭 활성화 비활성화를 구현하려고 하는데요

<ul id="ssch_sort">        <li><a href="<?php echo $sct_sort_href; ?>it_sum_qty&amp;sortodr=desc" class="btn01 <?php if($sort === 'it_sum_qty') { echo $selected; } ?>">판매많은순</a></li>        <li><a href="<?php echo $sct_sort_href; ?>it_price&amp;sortodr=asc" class="btn01 <?php if (($sort === 'it_price') && ($sortodr === 'asc')) { echo $selected; } ?>">낮은가격순</a></li>        <li><a href="<?php echo $sct_sort_href; ?>it_price&amp;sortodr=desc" class="btn01 <?php if (($sort === 'it_price') && ($sortodr === 'desc')) { echo $selected; } ?>">높은가격순</a></li>        <li><a href="<?php echo $sct_sort_href; ?>it_use_cnt&amp;sortodr=desc" class="btn01 <?php if ($sort === 'it_use_cnt') {echo $selected; } ?>">후기많은순</a></li>    </ul>