IE 11 requires a unit to be added to the third argument, the flex-basis property see MSFT documentation 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
IE 11 部分支持!
参见:can i use "-ms-flex"