Text change color depending on background

hi all.

im trying to create a heading that changes colour depending on the background. ive got half of my heading in a div with a bg black other half white and i need to get to change colour depending on the bg. there was something clonable i saw recently but i now cant find it. anyone have any ideas how to achieve this effect??? here is my site and i need to get slide heading to change colour.

any help would be great


Here is my site Read-Only: LINK
(how to share your site Read-Only link)

There is a JS library that does this, I can’t find it now. I know big HELP!!

You can do it with CSS. Look at this pen for example.