I would wait for more browser support - including the need for vendor
prefixes.
Note that Can I Use's support indicate the following:
Full Support (requires vendor prefixing):
34.39%
Partial support (some properties may not work at all or as expected):
42.14%
The Flexible Box Module is still in candidate stage so there could be
changes.
--
Al Sparber - PVII
The Finest Dreamweaver Menus | Galleries | Widgets
Since 1998