Thank you very much @elegantseagulls & @Jack for the clue.
I think I solved my problem:
ScrollTrigger.create({
trigger: '.nav-header',
start: 'top top',
endTrigger: 'footer',
end: 'bottom+=100vh bottom',
pin: true,
pinType: "fixed",
markers: true,
pinReparent: true,
pinSpacing: false
});