遍历了一下 flex 的各个属性,还没完全记住啊，省得下次用的时候这里查那里查了。
flex 的实现也在前面的 toy-browser 里面了。
- flex-direction: row | row-reverse | column | column-reverse
- flex-wrap: nowrap | wrap |wrap-reverse
- flex-flow: row nowrap
- justify-content: flex-start | flex-end | center | space-between | space-around
- align-items: flex-start | flex-end | center | baseline | stretch
- align-content: flex-start | flex-end | center | space-between | space-around | stretch
- order: <integer>
- flex-grow: <integer>
- flex-shrink: <number>
- flex-basis: <length> | auto
- flex: none| [<'flex-grow'> <'flex-shrink'>? || <'flex-basis'>]
- align-self: auto | flex-start | flex-end | center | baseline | stretch