@samrueby, you mentioned CSS flexbox to me and I think it was a terrific find. If we’re ok with not supporting old versions of IE, we can use it and completely bypass the Bootstrap/Foundation/etc. responsive grid techniques. Furthermore, it looks like flexbox took the same approach to columns as we did in FormItemList: they let you use whatever number of “units” you want. It also seems to support the vertical centering that we need. This is exciting!
Check these pages out: