JSFiddle - React, Tailwind, and code Playground

HTML

<div id="menu">
MENU
</div>

CSS

body {
  height: 2400px;
}
#menu {
  top: 0;
  position: sticky;
}

JavaScript

function checkScroll() {
  const scrollTop = window.pageYOffset || document.documentElement.scrollTop;
  const menu = document.getElementById('menu');
  menu.style.backgroundColor = scrollTop >= 1200 ? 'green' : 'red';
}

checkScroll();
document.addEventListener('scroll', checkScroll, false);