In your style.css make these changes:
What does that mean?
The value of z-index is more in navbar than in about section. More z-index value will give it more priority and it will be positioned on the top.
Read more about z-index at https://www.w3schools.com/css/css_z-index.asp
the first – you should handle images or gift or video size and convert to for web types because
your web site very big size and delay for loading ,
the second – Adding this might solve your problem
navbar disappears in second section. tried everything but does not work. I am not into coding btw. just complying to a subject requirement here is the file to get a better look
tried everything I understand at my level. it is driving me crazy.
If this works, feel free to accept the answer so that it could help others as well!