Php 滚动时，表格标题固定在顶部

我正在尝试设计一个HTML表格，在向下滚动时标题将固定在页面顶部，但它不起作用。下面是我的html代码

<table align="center">
<?php               
$select = "SELECT * FROM register where r_bid='".$_SESSION["id"]."' order by `name` ";
$result = mysql_query($select) or die(mysql_error());
$res = mysql_query("select * from regi_balic where b_id='".$_SESSION["id"]."'");
$row1=mysql_fetch_array($res);
$i=1;
echo'<thead><tr align="center">
<th width=3%><font size=3><strong>No.</strong></font></th>
<th width=10%><font size=3><strong>IC</strong></font></th>
<th width=12%><font size=3><strong>Name</strong></font></th>
<th width=12%><font size=3><strong>Reference</strong></font></th>
<th width=2%><font size=3><strong>Age</strong></font></th>
<th width=12%><font size=3><strong>Occupatin</strong></font></th>
<th width=5%><font size=3><strong>Mobile No</strong></font></th>
<th width=2%><font size=3><strong>Delete</strong></font></th>
</tr></thead>';
while($row = mysql_fetch_array($result))
{   
echo '<tbody><tr>
<td width="3%" align="center" ><font size=3>'.$i.'</font></td>
<td width="10%"><font size=3>'.$row1['name'].'</font></td>
<td width="12%" align="left" ><font size=3>
<a href="edit_detail.phpid='.$row["r_id"].'
&cand_id='.$_SESSION["id"].'&email='.$row["email"].'">'.$row['name'].'</a></font></td>
<td width="12%" align="center" ><font size=3>'.$row['reference'].'</font></td>
<td width="2%" align="right" style="padding-right:8px" >
<fontsize=3>'.$row['age'].'</font></td>
<td width="12%" align="right" style="padding-right:8px"><font 
size=3>'.$row['occupation'].'</font></td>
<td width="5%" align="right"><font size=3>'.$row['mob_no'].'</font></td>
<td width="2%"><a href="process_del_client.php?id='.$row['r_id'].'" onClick="return  
ConfirmSubmit(\'Are You sure ?\')"><img src = "images/delete.png"></a></td>
</tr></tbody>';
$i++;
}
echo '</table></div></center>';                 
?>
</div>

像这样的

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使thead-css位置：fixed/absolute.add-style位置：fixed用于表头。我已经这样做了，但是thead正在覆盖第一行。thead{position:fixed；width:78%；}我已经将其添加到了dstill中，面临同样的问题，现在thead会粘在页面的顶部，如果我试图将css样式设置为top:100px；到thead，然后它再次重写您的问题要求的第一行“一个HTML表格，在向下滚动时标题将固定在页面顶部。”但现在您不希望表格标题“固定在页面顶部”？您希望表格的标题在哪里？我的意思是表格标题应该固定在它的位置，行应该向下滚动

.list {
height: 409px;
width: 80%;
overflow: scroll;
}

table {
  height: 1000px; /* To force existence of a scrollbar. */
  background: yellow; /* To aid seeing boundaries. */
}

th {
  position: fixed; /* Fixes its position to the window. */
  top: 0; /* Sets that fixed position to stick to the top of the window. */
  width: 100%; /* Fills the width of the window; made it easier to see in your markup. */
  background: pink; /* To aid seeing boundaries. */
}