Dear Vlad,
when I go to the website itself (http://mutokukan.cz/mutokukan-ceska-republika) it is displaying the admin bar on top, as it should if I would be logged in – yet when I click on the admin interface entrance it still returns the same error: http://s24.postimage.org/6vr9kcld1/403_Forbidden.png.
Sincerely,
Andrew | Satori Studio