flex-direction 调整主轴方向(默认水平)
- row 、column、row-reverse、column-reverse
justify-content
- 调整主轴对齐方式 flex-start/flex-end/center/space-around/space-between
align-items 调整侧轴对齐方式
- flex-start、flex-end/center/stretch
flex-wrap
- 控制是否换行 wrap/nowrap
align-content 对flex-wrap:wrap 产生的换行控制
- flex-start/flex-end/center/space-between/space-around/stretch
flex 控制比例
- flex: 1/flex: 2
align-self 可覆盖父元素设置的 align-items
- flex-start/flex-end/center/stretch
