I tried creating a simple fade in navigation animation, basically following the simple steps in your video.
However, something strange is happening to the navigation (disappears) when it comes into contact with the testimonial slider section more than half way down the page. I'm not sure if the current interaction is getting mixed up by the slider code, if I didn't do the interaction correctly, or it's something else entirely.
I would really appreciate some clarity, advice, or insight on the issue.
Here is a visual of what is currently happening: