您需要设置页边距。这将防止页面内容呈现在为页眉和页脚分配的空间中。
@page { 
    margin: 120px 50px 35px 50px; 
}
您还需要将topon your设置header为负值以将元素推到边距之外。这同样适用于页脚。
top: -90px
您可以通过将下面的代码粘贴到DOMPDF Demo中来测试它
<html>
<head>
<style>
@page {
    margin: 120px 50px 80px 50px; 
}
#footer {
    position: fixed;
    bottom: -50px;
    height: 30px;
    background-color: #333399;
}
#header {
    position: fixed;
    top: -100px;
    width: 100%;
    height: 116px;
    background: url('http://ibadep.local/img/header2.png') no-repeat;
}
/* Type some style rules here */
</style>
</head>
<body>
<div id="header">
    This is the header
</div>
<div id="footer">
    This is the footer
</div>
<table>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
<tr>
<td>Column1</td><td>Column2</td><td>Column3</td>
</tr>
</table>
<!-- Type some HTML here -->
</body>
</html>