» IE 11 requires a unit to be added to the third argument, the flex-basis property see MSFT documentation
» Safari uses min/max width/height declarations for actually rendering the size of flex items, but it ignores those values when calculating how many items should be on a single line of a multi-line flex container. Instead, it simply uses the item's flex-basis value, or its width if the flex basis is set to auto. see bug
» In IE10 and IE11, containers with display: flex and flex-direction: column will not properly calculate their flexed childrens' sizes if the container has min-height but no explicit height property. See bug.
» IE 11 does not vertically align items correctly when min-height is used see bug
» Flexbugs: community-curated list of flexbox issues and cross-browser workarounds for them
» In IE 10, setting -ms-flex-flow: row wrap will not wrap unless display: inline-block is set on child elements.
» Firefox does not support Flexbox in button elements
» In IE10 the default value for flex is 0 0 auto rather than 0 1 auto as defined in the latest spec.
» In Safari, the height of (non flex) children are not recognized in percentages. However other browsers recognize and scale the children based on percentage heights. (See bug) The bug also appeared in Chrome but was fixed in Chrome 51