You are taking the CSS Generator option wrong, it doesn’t make any effect on the site that will be visible to you when you save it. It is used to limit the CSS to load on the website.
This means that you can only load the CSS of the specific elements by selecting not all.
@Giulio Please create a separate topic and explain the issue in detail what you actually require with the CSS generator with the help with some relevant screenshots to check it myself and help you out accordingly.