为何需要设计系统以及如何实践设计系统？"Design System"

参考：

- [如何评价微软在 Build 2017 上提出的 Fluent Design System？ - 知乎](https://www.zhihu.com/question/59724483)
- [design system - Google Search](https://www.google.com/search?hl=en&as_q=design+system&lr=lang_zh-CN)
- [design system - Instapaper](https://www.instapaper.com/search?q=design+system)

现有的工具：
https://github.com/react-theming/storybook-addon-material-ui
https://github.com/storybooks/storybook/tree/master/addons/knobs

https://github.com/salesforce/design-system-react
https://react.lightningdesignsystem.com/

https://antd-live-theme.firebaseapp.com/

https://vueds.com/example/
https://github.com/viljamis/vue-design-system