I have duplicated Sidney's work to use on my portfolio page for etrdesign.com(which will be looking like this page). Unfortunately, I didn't have time to properly implemented it on my site but it seems there several people looking for it so I tried to show it here. I changed the code and tried several things with no knowledge of JS. Sorry in advance if there are some problems.
PS. Website is also using Fullpage.js (Codes of fullpage.js is not on designer side. It's on Custom Codes part of Project Settings)