scroll 시 특정 위치에서 fixed 되는 영역 만들기

function centerElement(elementId) {
    const element = document.getElementById(elementId);
    const parent = element.parentElement;

    if (window.scrollY > parent.offsetTop - ((document.documentElement.clientHeight - element.offsetHeight) / 2)) {
      element.style.position = "fixed";
      element.style.top = "50%"
      element.style.left = "50%"
      element.style.transform = "translate(-50%, -50%)"

    }
    else {
      element.style.position = "relative"
      element.style.top = "initial"
      element.style.left = "initial"
      element.style.transform = "initial"
    }
  }