How to use inline css in mpdf if we don't have external stylesheet or any .css file

I am using inline css in the template but it is not working while generating a pdf through mpdf. So please tell me how can I access it

$mpdf = new \Mpdf\Mpdf();
$mpdf->SetDisplayMode('fullpage');
$mpdf->WriteHTML($html);
ob_clean();
$mpdf->Output('PaySlip.pdf', 'd');
exit();

source https://stackoverflow.com/questions/72756212/how-to-use-inline-css-in-mpdf-if-we-dont-have-external-stylesheet-or-any-css-f