Bootstrap collapsed navbar not working in this [PEN](http://codepen.io/anon/pen/GzAnv “”) . after re-size browser nothing happening.
Today is my first day to use bootstrap and i am very excited about it but it seems that it is very difficult to understand. it’s being 8 hours when i stuck at navbar. bootstrap example is easy but to create professional site like [these](https://wrapbootstrap.com/ “”) are impossible for now .
