Thanks for your feedback. Actually Bootstrap v4 provides an opinion to use flex box instead of the traditional grid. http://v4-alpha.getbootstrap.com/getting-s

Thanks for your feedback. Actually Bootstrap v4 provides an opinion to use flex box instead of the traditional grid. http://v4-alpha.getbootstrap.com/getting-started/flexbox/ http://v4-alpha.getbootstrap.com/getting-started/flexbox/ I would say your suggestion is good. I don't have a convincing reason that `container-side` being a part of the framework. I'll consider to remove it. What kind of content is never visible on mobile? `Scan the QRCode to view on mobile` and `Go to top` is a kind of this content. Why does it have to be on the side? I think it's a good design to guide people to view on mobile. Or where do you think it can be? Thanks!