stelfair the regular way but the stylings as you all have it on your demo is not how my listing is looking
You may kindly contact the template provider whose template you have assigned as to how to include external css file reference in the specific template framework as the specific php reference works fine with T3 framework while adding it above </head> element
<?php
// DTREGISTER CSS
$this->addStyleSheet(JUri::base(true) . '/components/com_dtregister/templates/default/assets/css/main.css');
?>
Majorly, External css file i.e. /components/com_dtregister/templates/default/assets/css/main.css isnt embedding due to which layout for the specific component menu type isnt getting styled as envisaged
Would also report about external css file of specific component not getting linked by default with JA Dev. Team and look forward to be fixed in upcoming version update 🙂