Dompdf overlapping the images

I am trying to convert a products gallery images into PDF using dompdf , but it overlaps images instead of showing them on next line (for the solution, I tried <br> also but did not work for me)

if(isset($data) && count($data)>0){
$html="<link rel='stylesheet' href='".get_template_directory_uri()."/assets/css/woocommerce.css'>";
$html.="<link rel='stylesheet' href='".get_template_directory_uri()."/style.css'>";
$html.="<div  style='text-align: center;'><h1>".$project_title."</h1><span><h3>".$project_sub_title."</h3></span></div>";
$html.='<div id="pdf_main"><ul class="products clearfix products-3 pdf_class">';
$counter=1;
while  ($data = mysql_fetch_assoc($result)) {
$html.='<li class=" product type-product status-publish has-post-thumbnail product_cat-bedroom  instock shipping-taxable purchasable product-type-simple">
<img src="'.$data['img'].'" class="attachment-shop_catalog size-shop_catalog">
 </a>
 <div class="product-details">
  <div class="product-details-container">
   <h3 class="" data-fontsize="16" data-lineheight="24">'.$data['product_title'].'</h3>
</div>
</div>
</li>';
}
$html.="</ul></div>";
$options = new Options();
$options->set('isRemoteEnabled', true);
$dompdf = new Dompdf($options);
$dompdf->loadHtml($html);
$dompdf->setPaper('A4', 'portrait');
$dompdf->render();
$dompdf->stream('Products.pdf');
$output = $dompdf->output();
}

Here is css

.products li.product { background-color: transparent; }
.products-3 > li:nth-child(3n+1) { clear: both;    content: " ";    display: block;}
 .products li { border-color: #ebeaea;}
 .products-3 > li { float: left;    margin-bottom: 11px;    margin-right: 1%;    width: 32.6%;}
.products > li {  -moz-border-bottom-colors: none;    -moz-border-left-colors: none;    -moz-border-right-colors: none;    -moz-border-top-colors: none;    border-color: #efefef;    border-image: none;    border-style: solid;    border-width: 1px 1px 2px;}
.product {    position: relative;}

See 4th image is half cut and also 5th is not showing, in my css i am clearing float after 3rd products but its not working and over lapping the images

Answer

After lot of dubbing i came to know that <li> was getting auto with that is why it was over lapping. I gave it fixed width and it was working and showing perfect grid

$html.='<li class=" product type-product status-publish has-post-thumbnail product_cat-bedroom  instock shipping-taxable purchasable product-type-simple">
<img src="'.$data['img'].'" class="attachment-shop_catalog size-shop_catalog">
 </a>
 <div class="product-details">
  <div class="product-details-container">
   <h3 class="" data-fontsize="16" data-lineheight="24">'.$data['product_title'].'</h3>
</div>
</div>
</li>';