Generar documento pdf con html

hola buenas a todos
les traigo una libreria esta bastante util se trata como podemos generar un documento pdf
le saque partido de unos de mis proyectos actualmente estoy desarrollado un sistema escolar.
les paso capturas del apartado de exportar informacion


Codigo

<?php 
	require("../../Connections/Conexion.php");
	require("lib/pdf/mpdf.php");
	if(!$_GET['id'] || !$_GET['dni']){header('location:'.$urlWeb);}
	$idstudent = utf8_decode(strip_tags($_GET['id']));
	$dnistudent =  utf8_decode(strip_tags($_GET['dni']));
	mysql_select_db($database_conexion, $conexion);
	$query_DatosStudents =  sprintf("SELECT * FROM estudiantes WHERE user_id=%s AND dni=%s",
	GetSQLValueString($idstudent, "text"),
	GetSQLValueString(($dnistudent), "text"));
	$DatosStudents = mysql_query($query_DatosStudents, $conexion) or die(mysql_error());
	$row_DatosStudents = mysql_fetch_assoc($DatosStudents);
	$totalRows_DatosStudents = mysql_num_rows($DatosStudents);
	if($totalRows_DatosStudents <=0){header('location:'.$urlWeb);}
	$_SESSION['padre_id'] = $row_DatosStudents['padre_id'];
 

$mpdf= new mPDF('c','A4');
$css = file_get_contents('lib/style.css');
$mpdf->WriteHTML($css,1);
$html = '
<header class="clearfix">
		<div class="container">
			<figure>
				<img class="logo" src="data:image/svg+xml;charset=utf-8;base64,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" alt="">
			</figure>
			<div class="company-info">
				<h2 class="title" style="margin-left:10px;">'.$nombreWeb.'</h2>
				</div>
		</div>
	</header>

	<section>
		<div class="details clearfix">
			<div class="client left">
				<p>Alumno:</p>
				<p class="name">'.$row_DatosStudents['nombre_apellido'].'</p>
			</div>
			<div class="data right">
				<div class="title">reporte</div>
				<div class="date">
					'.date('d').'-'.date('n').'-'.date('Y').'<br>
				</div>
			</div>
		</div>
		<div class="container">
			<div class="table-wrapper">
			<h3>Informacion Del alumno</h3>
			<table class="table table-striped table-hover ">
  <thead>
    <tr>
      <th><strong>Apellido Nombre</strong></th>
      <th><strong>Direccion</strong></th>
      <th><strong>Documento</strong></th>
     <th><strong>Nacimiento</strong></th>
    </tr>
  </thead>
  <tbody>
    <tr class="warning">
      <td>'.$row_DatosStudents['nombre_apellido'].'</td>
	 <td>'.$row_DatosStudents['direccion'].'</td>
	<td>'.$row_DatosStudents['dni'].'</td>
	<td>'.$row_DatosStudents['nacimiento'].'</td>
    </tr>
   
  </tbody>
</table>
			
			</div>
			
			
			<br>
<br>
	<div class="table-wrapper">
			<h2>Curso:</h2>
			<table class="table table-striped table-hover ">
  <thead>
    <tr>
      <th><strong>#</strong></th>
     <th><strong>Nombre curso</strong></th>
    </tr>
  </thead>
  <tbody>
    <tr class="warning">
	<td>'.$row_DatosStudents['curso_id'].'</td>
	<td>'.utf8_encode(($row_DatosStudents['curso_id'])).'</td>
    </tr>
   
  </tbody>
</table>
			<br>
<br>
<br>

'.report_padre($_SESSION['padre_id']).'
</div>
		</div>
	</section>
<br>

	<footer>
		<div class="container">
		
			<div class="notice">
				<br>
<br>

			</div>
			<div class="end">$infocredit</div>
		</div>
	</footer>

';

$mpdf->writeHTML($html);
$titulo = $row_DatosStudents['nombre_apellido'].' - '.$row_DatosStudents['dni'].'.pdf';
if(isset($_GET['preview'])){
if($_GET['preview']=1){
$mpdf->Output($titulo,'I');
}
}else{
$mpdf->Output($titulo,'D');
}


 ?>

en la variable $_GET['preview']
seriea si quisieras previsualizar el pdf
y
Output = $titulo , D seria download = descargar archivo
yo le doy la posibilidad de descargar el documento si se desea



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