Change Margin for Packing List

Hi,

I have followed your instruction to change the packing list to 4×6 label with the following code.

add_filter( 'wpo_wcpdf_paper_format', 'wcpdf_custom_inch_page_size', 10, 2 );
function wcpdf_custom_inch_page_size($paper_format, $template_type) {
    if ($template_type == 'packing-slip') {
	    // change the values below
	    $width = 4; //inches!
	    $height = 6; //inches!
	 
	    //convert inches to points
	    $paper_format = array( 0, 0, $width * 72, $height * 72 );
    }
    return $paper_format;
}

How do I adjust the margin of packing list? I tried the following code but it is still following the setting in style.css file.

add_action( 'wpo_wcpdf_custom_styles', 'wpo_wcpdf_custom_styles', 10, 2 );
function wpo_wcpdf_custom_styles ( $document_type, $document ) {
      $document = wcpdf_get_document( $template_type, $order );
      if ($template_type == 'packing-slip') {
        ?>
            td.header img {
                max-height: 0.25cm;
                width: auto;
            }

            @page {
                margin-top: 0.1cm;
                margin-bottom: 0.1cm;
                margin-left: 0.1cm;
                margin-right: 0.1cm;
            }

            <?php
    }
}