flex常用css属性封装

.flex-row {
	display: flex;
	flex-direction: row;
}
.flex-column {
	display: flex;
	flex-direction: column;
}
.j-c {
	justify-content: center;
}
.j-s-b {
	justify-content: space-between;
}
.j-s-a {
	justify-content: space-around;
}
.a-c {
	align-items: center;
}