dompdf library using codeigniter doesn't work html and css

Question

I am using dompdf library for downloading pdf format. The first created a pdf template in HTML format then a function used to call the dompdf library and viewing the function of download pdf. But it doesn't work CSS and HTML with tags. Below my code of the function of the controller

$this->load->library('Pdf');
    $id=$this->uri->segment(3);
     $data['title']='Invoice';
    $data['invoice_view']= $this->Invoice_Model->get_purchaseorder_by_id($id);
    $this->load->view('components/pdftemplate',$data);
    $html = $this->output->get_output();

     $dompdf=new DOMPDF();
     $dompdf->load_html($html);
     $dompdf->render();
     $dompdf->stream("invoice.pdf");enter code here

then created html template

<div class="block">
    <div class="row">
        <div class="col-md-6">
            <p>company Logo</p>
        </div>
        <div class="col-md-6"  style="float:left;color:red;">
            <p>Purchase Order</p>
        </div>
    </div>
    <div class="app-heading app-heading-small">                                
        <div class="title">
            <h5><?= $title;?></h5>
        </div>
    </div>
    <?php foreach($invoice_view as $inv):?>
     <div class="row">
            <div class="col-md-6">
               <div class="app-widget-informer">
                    <div class="title">To:<?= $inv->client_company_name;?></div>
                    <div class="tinyintval"><?= $inv->address;?></div>    
                    <div class="tinyintval"></div>                                                                             
                    <div class="tinyintval">Phone:<?= $inv->phone;?></div>
                    <div class="tinyintval">Email:<?= $inv->email;?></div>
               </div>
          </div>
            <div class="col-md-6">
                <div class="app-widget-informer">   
                    <div class="tinyintval">Po#:<?= $inv->invoice_id;?></div>                                        
                    <div class="tinyintval">Po Date:<?= $inv->issue_date;?></div>                                         
                </div>
            </div>                                
    </div>
                    <table class="table table-bordered" >
                        <thead>
                            <th>slno </th>
                            <th> Description</th>
                            <th>Unit Price</th>
                            <th>Quantity</th>
                            <th>Cost</th>
                            <th>Tax %</th>
                        </thead>
                       <tbody>
                       <?php foreach($inv->tableinvoice as $tabin):?>
                                <tr >
                                    <td>
                                    <?= $tabin->id; ?>
                                    </td>       
                                    <td>
                                    <?= $tabin->description; ?>
                                     </td>
                                    <td>
                                    <?= $tabin->quantity; ?>
                                    </td>
                                    <td>
                                    <?= $tabin->unitprice; ?>
                                    </td>
                                    <td>
                                    <?= $tabin->cost; ?>
                                    </td>
                                    <td>
                                    <?= $tabin->tax; ?>
                                    </td>
                               </tr>
                               <?php endforeach;?>      
                        </tbody>
                     </table>
                   <?php endforeach;?>
    </div>

but getting a text format doesn't work css and html styles.