start indicates left alignment with extra space towards the right side, a value of end indicates right alignment with extra space to the left, a value of center indicates center alignment with extra space split evenly on either side, and a value of justify indicates that the outer elements should be aligned on the left and right, with space added evenly between the elements.
Similarly, for elements whose children are aligned vertically, a value of start indicates that the elements should be aligned to the top, a value of end indicates that the elements should be aligned to the bottom, and so on.
This property is similar to -webkit-box-align, which specifies alignment in the opposite direction from the direction of orientation.
This property applies only to flexible box layouts. For more information about flexible boxes, see http://www.w3.org/TR/css3-layout/.
]]>