User Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/29.0.1521.3 Safari/537.36 Steps to reproduce: A container div with "display: box" and "flex-flow: column" two div boxes with fixed height and "flex: none", while the third div box has "flex: 1 1 auto" (so it should take the rest of the container height. See it here: http://jsfiddle.net/ibcaliax/gDv4t/ Actual results: The result is completely wrong in Firefox (but it is properly displayed in Chrome and Opera 12).
Using "flex-direction" instead of "flex-flow" shows it correctly. It seems a bug since "flex-flow" is a shorthand for setting the "flex-direction" and "flex-wrap" properties, with default value of "row nowrap".
Confirmed with Mozilla/5.0 (Windows NT 6.1; WOW64; rv:26.0) Gecko/20100101 Firefox/26.0 ID:20130814030204 CSet: 3c61cc01a3b1 Will be fixed by Bug 702508.