Backround color not change on scroll

I have struggled with this header for a while. It acts strangely and shifts over to the right after I scroll up and down. Then it ends up bunched up and overlapping a bar at the top of the screen instead of returning to normal size and position.

I also wanted the background to change to white upon scroll and it doesn’t work.

I’ve used your plugin on many sites and this is the first time I’ve tried it on a transparent header with a background section with a negative top margin.

What am I missing here?

The page I need help with: [log in to see the link]