Sticky Header Issue in Mobile (Botiga)

Hello, I have been looking for CSS codes all over the internet for my header to appear sticky in mobile/tablet just like in Laptop/Desktop view.
When scrolling down the header changes color from black to white and all icons change color from white to black.
I know it can be challenging, but Please help me with this.

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


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