固定表头简单实现

<style>
Table
{
 border:none;
 width:100%;
 border-collapse:collapse;
}

Td
{
 border:solid 1px #ccc;
 background-color:White ;
 padding:4px;
 font-size:13px;
}
Th
{
 border:solid 1px #ccc;
 background-color:gray ;
 padding:4px;
 font-size:13px;
        width:Auto;
 
}
</style>

<div style="height: 150px; overflow: auto;">
<table border=0>
    <tr  style="background-color:gray;border-bottom:solid 1px blue;position:relative;top:expression(this.offsetParent.scrollTop);">
         <th>
            head
        </th>
 <th>1</th>
    </tr>   
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
</table>
</div>

firefox:
<div style="height: 150px; overflow: auto;">
<table border=1>
    <tr  style="position:fixed;background-color:gray;">
        <th>
            head
        </th>
 <th>1</th>
    </tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>   
 <tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
<tr><td>1</td><td>2</td></tr>
</table>
</div>