点击title
title,li,box,都增加选中类名on
列表只有一个选中效果,其他不受影响
<ul class="list">
<li class="on">
<h4 class="title on">11</h4>
<div class="box on">11</div>
<li>
<li>
<h4 class="title">22</h4>
<div class="box">22</div>
<li>
<li>
<h4 class="title">33</h4>
<div class="box">33</div>
<li>
</ul>