Christoph R. I suppose I could see it potentially being bad for SEO if not implemented correctly. Within a section or CMS item you can set certain sections is visibility hidden - so maybe on mobile you make the desktop version hidden - this is different than display: none because display: none is CSS - but this is at the DOM (document object model) level - so if something is marked as "hidden" - it will not even render on the page or within the code. And with that, crawlers will not flag this for duplicate content.