Adds smooth scrolling to internal links with optional offset for top header - https://lukasznojek.com/blog/2019/08/automatically-enhance-headers-with-hierarchy-and-links/

smoothScrolling.js

/**
 * Adds smooth scrolling to internal links with optional offset for top header
 *
 * @param {number} offset - optional offset to add when scrolling
 * @param {number} duration - the duration of the animation, by default 800
 * @param jQuery - reference to the jQuery
 */
function smoothScrolling(offset = 0, duration = 800, jQuery = $) {
	jQuery('a').click(function() {
		jQuery('html, body').animate({
			scrollTop: jQuery( jQuery(this).attr('href') ).offset().top - offset
		}, duration);
		return false;
	});
}