that is one of the many responsive frameworks that are out there. I believe you could also achieve the same with bootstrap[^] or an even simpler framework like unsematic[^] could be used.
the nice thing with either of those is that you are concentrated on web development and not focused on web development only being mobile development.
if you sprinkle in some angular you have the complete package for web development that could also be targeted towards mobile development as well.
If I have the choice I prefer sailing in ever changing waters.
So although mainframes and consumer electronics firm/softwares have their appeals, fast moving and close to the client interactions happen much more while developing for the web and for the mobile platforms.
I like people and all the problems that they bring. Helps me keep in mind what I'm working for/to!