html - :nth-child() not working

Question

我正在尝试使用 :nth-child(5); 拉伸(stretch)背景上的图像以进行第三次打印。但它没有捕获它。我做错了什么吗？

table#OppPracticeOverview tr th {
    padding:5px !important;
    background-color:transparent;
}
table#OppPracticeOverview tr th img {
    width:47px;
    height:22px;
    float:left;
    margin:-5px 0 0 -42px;
    position:absolute;
    z-index:-1;
}
table#OppPracticeOverview tr th img:nth-child(5) {
    width:110px;
    height:22px;
    float:left;
    margin:-5px 0 0 -105px;
    position:absolute;
    z-index:-1;
}

HTML:

<table id="OppPracticeOverview">
<tbody>
    <tr>
        <th>
            Patients
            <img src="/images/img-CCCCCC.png">
       </th>
       <td>
       <th>
           On Hold
           <img src="/images/img-CCCCCC.png">
        </th>
        <td>
        <th>
           Reattribution Request
          <img src="/images/img-CCCCCC.png">
       </th>
       <td>
   </tr>
</tbody>

Answer 1

你几乎是对的，只需将 nth-child 从 img 移动到 th 即可，如下所示:table#OppPracticeOverview tr th :nth-child(5) img

演示:http://jsfiddle.net/G79X9/1/