I need help for my first portfolio

There are a lot of errors that I cannot fix
First of all, the navbar fixed top doesnot work on mobile
Secondly, i was looking for a solution to resize text on mobile
The last one is the scrollspy. When i use it. The above content will be lost. Yet it works perfectly on laptop
Here is my portfolio link: http://codepen.io/hungnguyen1895/full/rrOyLL/

The mobile code is working as it should. The mobile version has a “hamburger” menu (the three lines at the top of the screen). If you click on this, it will reveal the navigation links. This is a pretty standard type of menu of mobile devices because it saves space on smaller screens.

Hope this helps!