版本：
文件：
- https://cdn.bootcdn.net/ajax/libs/flexnav/1.3.3/css/flexnav.css
- https://cdn.bootcdn.net/ajax/libs/flexnav/1.3.3/css/flexnav.min.css
- https://cdn.bootcdn.net/ajax/libs/flexnav/1.3.3/js/jquery.flexnav.js
- https://cdn.bootcdn.net/ajax/libs/flexnav/1.3.3/js/jquery.flexnav.min.js