|Perl: the Markov chain saw|
I'm reasonably certain that the "flex" to which Lady Aleena refers, is the W3C's "CSS Flexible Box Layout" module. If you look at the CSS listing (top, right-hand panel) in the "new code", you'll see:
[Note: I see the content of the new code linked page has changed since I viewed it yesterday (when I approved the node). I don't know exactly what changed; however, the overall layout is different (links moved from the top of the page to a new side bar; new content in this side bar). Obviously, I have no idea which version you may have seen.]
This CSS module is a work in progress. It does seem to have stalled close to two years ago. This may affect the choice to use it. From the "Status of this document" section:
My intention is not to dissuade usage — I've certainly used plenty of W3C's Candidate Recommendations over the years — but I felt it was important to advise the current, non-stable status of this CSS module.
For what it's worth, I don't mind the general direction of this proposed change; although, I preferred what I saw yesterday, to what I'm seeing today.