... Ah, sorry for the confusion
after having the toolkit setting in place, all access to the file style.css was blocked, but the html pages were shown, but obviously not in the correct format.
My understanding of the toolkit entry was, that access to the file style.css is blocked, once it is directly entered in the url, but not if it is used by an html page to format the display.
But as i wrote, no access to this file was possible at all, but the website was correctly displayed.
Hope this helps a little bit ...
Many tx.
Cheers
Kai