Hi Bozhidara,
Thank you for your response and explanation.
We do not use tab headers in the application.
::part(pane-header) in the css works fine in the project, but the active state does not. This also applies to ::part(pane-header-content), which works fine, but ::part(pane-header-content active) does not. Do you have any idea what this could be? I may not be the first to run into this.
(I have also put the code in the example, it also works properly there.)
I look forward to your response.
Thanks in advance.