Affino Responsive Design Centre is a DIY Design Implementation Utility which is key to building responsive-design layouts. It makes use of currently 28 Design Element widgets which can be arranged together in Design Object grids to produce the required dynamic page layouts - scaled to specified Breakpoints.
NOTE - there are other technicalities here, Presentation Styles / Template Management which are connected to content display, also note that the Channel structure comes preloaded with various layouts for Channel-type specific content, and as per Prime Content Design Element deployed on page.
Fully optimised, minimal code footprint, wholly integrally and seamlessly part of the core solution. Everything dovetails together with the minimum of fuss, and the maximum system integrity and versatility. There are other layout design platforms out there, but none so well anchored into their core solutions, and with the same degree of flexibility.
An almost infinite variety of design can be achieved - some examples: