adjustScroll = function () {
  // Sticky nav selector (you'll have to provide your own selector)
  const nav = document.querySelector('header>nav');

  if (location.href.indexOf("#") >= 0) {
    // Find the name of the anchor
    let n = location.href.substr(location.href.indexOf("#")+1);

    // Find the anchor by name, if it exists
    let a = document.querySelector('a[name="'+n+'"]');
    if (!a) {
      return;
    }

    // Set y value as y-value of the anchor, offset by the header height
    let y = a.offsetTop;
    y -= nav.height + 10;

    // Scroll to the y position
    window.scrollTo(0, y);
  }
}

// Call it wherever you need to call it
adjustScroll();