Hi Stefanie,
Is it correct, that I would need an inner Container only for my frontpage sections?
Yes, your understanding is generally correct.
Only in some cases, let’s say you have a container block in a non-home page which is not full width, then you add a background image with opacity or a background image and gradient, in another word, the background has a pseudo-element, then you will need to add an inner container which is set to position:relative, so that your content can be shown above the pseudo-element.