mixin horizontal
	display flex
	flex-direction row

mixin horizontal-wrap
	display flex
	flex-flow row wrap

mixin horizontal-wrap-center
	horizontal-wrap
	justify-content center

mixin vertical
	display flex
	flex-direction column

mixin vertical-wrap
	display flex
	flex-flow column wrap

mixin vertical-wrap-center
	vertical-wrap
	align-items center