Can't style popup add to basket

When I add a item to my cart there opens a popup with 2 links. Go on shopping & To Cart.
This file has the url domainname.ext/productcategoriename/checkout/notice/tmpl-component

However in the source I see in the head section So no link to my own template and also this popup does not see the system template because it is going to:

productcategoriename/templates/system/css/template.css instead of templates/system/css/template.css

How can I change this so this popup does use my own template css file(s)?

Hi,

The link to the checkout should be fine. It doesn't work ? What happens when you click on it ? If you want your checkout to be displayed in a specific menu, you should use the option "force a menu on checkout" of the Checkout tab of the configuration.

The popup is actually displayed by the component.php file of your template. If the CSS of your template is not in the popups, it's highly likely that the component.php file of your template is not correctly done. I would advise you to contact your template provider's support so that they can tell you what to do as we don't know how they did it.