Well this is embarrassing...
You're currently on a web browser that does not support the most recent version of the CSS Flexible Box Model.
Upgrade your browser and have a nice day! Supports latest version of Flexbox unprefixed:

Opera 12.1+

Supports latest version of Flexbox prefixed:

Chrome 21+

Support for latest vesion of Flexbox coming soon!

Firefox 20+

Internet Explorer [?]

Safari [?]

Mobile support for the latest version of Flexbox is absolutely not fantastic, but is improving.
View full table of support for Flexbox on Can I use...