Navbar design change, how?

Tell us what’s happening:

The Navbar’s background color, logo and list names changes with every change in section. I’m really interested to put this design in one of my projects but, don’t know where to learn it. Can someone help?

Above is the link what I’m trying to mean. It has the source code but, it’s hard for me to understand and don’t know where to start.

In that case I would recomend you to do the HTML/CSS course here onto FCC. Just use the link: https://www.freecodecamp.org to get started it might take some time but, you will be able to learn every thing you need to know eventually.
https://www.w3schools.com/html/default.asp
Also can be a huge help here

I’m currently in the JS section right now in FCC., done with HTML and CSS. How will that help me with navigation bar color translation?