Invert Dynamic Header Colours

Hey guys

My clients homepage is set up with a picture of her clinic and i have the header set to dynamic so the background is transparent and the text is white. When we scroll down it changes the background to black and keeps header text white. Could any of you help me out with the code needed so that when we scroll down it inverts the colours so the header background is black and the font and logo turn black?

An example of what i mean is shown on this site https://www.24seventalent.com/?source=blog.hubspot.com except their logo doesnt change. If this is not possible then i might have to pick a logo colour that shows up on dark and light backgrounds.

my site is www.ambermarieskin.co.uk

i only want the inversion to happen on the homepage. thanks a lot guys

Ross