.u-flex {
	display: flex;
	flex-direction: row;
	align-items: center;
}

/* 换行 */
.u-flex-wrap {
	flex-wrap: wrap;
}

/* 不换行 */
.u-flex-nowrap {
	flex-wrap: nowrap;
}

/* 垂直居中 */
.u-col-center {
	align-items: center;
}

/* 顶部对齐 */
.u-col-top {
	align-items: flex-start;
}

/* 底部对齐 */
.u-col-bottom {
	align-items: flex-end;
}

/* 左边对齐 */
.u-row-left {
	justify-content: flex-start;
}

/* 水平居中 */
.u-row-center {
	justify-content: center;
}

/* 右边对齐 */
.u-row-right {
	justify-content: flex-end;
}

/* 水平两端对齐，项目之间的间隔都相等 */
.u-row-between {
	justify-content: space-between;
}

/* 水平每个项目两侧的间隔相等，所以项目之间的间隔比项目与父元素两边的间隔大一倍 */
.u-row-around {
	justify-content: space-around;
}