Change menu text colour on scroll

Hi,

I have been able to change the colour of the main menu font using <span style=”color: #9c1e1f;”>Menu Name</span> but what I really am hoping to achieve is to have it as white over the background video, then on scroll change to red as it goes into the black header.

I have seen this before, does anyone know how I can do this please?

Thank you!

Steve