403 forbidden

Yes, http://deb.great-site.net/bootstrapcards.html works fine. You have no index file though; so the server tries to look for one, and failing that, redirects you to 403.

As described in the article I linked above, if you want bootstrapcards.html to be your index file, you can either rename it to index.html, or set a DirectoryIndex rule:

If you just want a directory listing of your files, this is also covered: