V4 page structure: which element should be used as the main section wrapper? Сlassic Container or atomic Flexbox?

Describe the Problem I'm building new sites with the V4 Atomic editor, and it's not clear to me how pages are supposed to be structured now. The editor currently gives me two ways to build a layout: • the classic containers (Flexbox / Grid container) • the new atomic elements (Div element, Flexbox) Both work, and I can even mix them on the same page. For example, I can put atomic elements inside a classic container or classic widgets inside a Div element. But there is no guidance on which approach is recommended: Should new pages be built with atomic elements only, or is it fine to keep using classic containers? Is mixing them on the same page an intended, long-term supported way to build, or just a temporary state during the transition? If classic containers will eventually be replaced, will there be a way to convert existing layouts? Without this, I'm not sure my pages are built "the right way", and I'm worried I'll hav…