feat: css flex布局

README.md

@@ -250,6 +250,15 @@ JavaScrip 在变量被创建时分配内存，并在对象不再使用时自动
   - [ ] [GC in v8](https://github.com/lrlna/sketchin/blob/master/guides/garbage-collection-in-v8.md)
   - [ ] [JavaScript 工作原理：内存管理 + 处理常见的 4 种内存泄漏](https://blog.sessionstack.com/how-javascript-works-memory-management-how-to-handle-4-common-memory-leaks-3f28b94cfbec)，另有[中文版](https://juejin.cn/post/6844903519078580238)
 
+## CSS
+### flex
+- [ ] 文档
+  - [ ] [flex](https://developer.mozilla.org/en-US/docs/Web/CSS/flex)
+- [ ] 推荐文章
+  - [ ] [A Complete Guide to Flexbox](https://css-tricks.com/snippets/css/a-guide-to-flexbox/)
+  - [ ] [Flexbox布局中不为人知的细节](https://juejin.cn/post/6938292463605907492)
+
+
 ## React
 
 ### 合成事件