仅供新手参考学习，欢迎大家提出更多的实现方法。
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"/TR/xhtml1/DTD/xhtml1-transitional.dtd">
< html xmlns="/1999/xhtml">
< head>
< meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
< title>模拟表格对角线</title>
< style type="text/css">
*{padding:0;margin:0;} caption{font-size:14px;font-weight:bold;}
table{ border-collapse:collapse;border:1px #525152 solid;width:50%;margin:0
auto;margin-top:100px;}
th,td{border:1px #525152
solid;text-align:center;font-size:12px;line-height:30px;background:#C6C7C6;}
th{background:#D6D3D6;} /*模拟对角线*/
.out{ border-top:40px #D6D3D6 solid;/*上边框宽度等于表格第一行行高*/
width:0px;/*让容器宽度为0*/
height:0px;/*让容器高度为0*/
border-left:80px #BDBABD solid;/*左边框宽度等于表格第一行第一格宽度*/
position:relative;/*让里面的两个子容器绝对定位*/ }
b{font-style:normal;display:block;position:absolute;top:-40px;left:-40px;width:35px;} em{font-style:normal;display:block;position:absolute;top:-25px;left:-70px;width:55x;} .t1{background:#BDBABD;}
< /style>
< /head>
< body>
<table>
<caption>用div+css模拟表格对角线</caption>
<tr>
<th style="width:80px;">
<div class="out"><b>类别</b><em>姓名</em></div>
</th>
<th>年级</th>
<th>班级</th>
<th>成绩</th>
<th>班级均分</th>
</tr>
<tr>
<td class="t1">张三</td>
<td>三</td>
<td>2</td>
<td>62</td>
<td>61</td>
</tr>
<tr>
<td class="t1">李四</td>
<td>三</td><td>1</td>
<td>48</td><td>67</td>
</tr>
<tr>
<td class="t1">王五</td>
<td>三</td><td>5</td>
<td>79</td><td>63</td>
</tr>
<tr><td class="t1">赵六</td><td>三</td><td>4</td><td>89</td><td>66</td></tr> </table>
< /body>
< /html>。