版本：
文件：
- https://cdn.bootcdn.net/ajax/libs/prettyCheckable/2.1.2/prettyCheckable.css
- https://cdn.bootcdn.net/ajax/libs/prettyCheckable/2.1.2/prettyCheckable.min.js
- https://cdn.bootcdn.net/ajax/libs/prettyCheckable/2.1.2/sprites-sfa68604977.png