Flexible Box
CSS Flexbox Examples
http://umaar.github.io/css-flexbox-demo/
A Complete Guide to Flexbox
https://css-tricks.com/snippets/css/a-guide-to-flexbox/
Working with flexbox: The new specification
http://www.adobe.com/devnet/archive/html5/articles/working-with-flexbox-the-new-spec.html
Advanced Cross-Browser Flexbox
https://dev.opera.com/articles/advanced-cross-browser-flexbox/