Just a FYI, the new viewport based vw, vh and vmin units can easily give the same results. Of course you’d end up supporting only newer browsers as there is serious lack in mobile browser support: http://caniuse.com/#search=viewport
Hopefully quite usable by next year. Right now I came up with this example to show how one could use viewport units and give percentages for browsers that don’t support it: http://codepen.io/Merri/pen/gimKw
Also shows how you can get centered stuff without any position properties. I tried to comment the CSS to give an idea of all the minor details.