https://www.universeum.se/themes/custom/citybreakweb/cb_universeum/js/header.skin.js?tm9ti5

1/**
2 * Header Skin / Theme ClassName
3 * body.show-header-skin-transparent : Styled e.g Header - White logo, transparent background
4 */
5(function ($, Drupal, drupalSettings) {
6  'use strict';
7  jQuery(document).ready(function ($) {
8    var bodyClassName = '';
9    function setHeaderSkinClassName() {
10      if ($('.layout-header.position-fixed').length || $('.layout-header.position-absolute').length) {
11        bodyClassName = 'show-header-skin-transparent';
12      }
13      $('body').addClass(bodyClassName);
14    }
15    $(function () {
16      setHeaderSkinClassName();
17    });
18    $(window).on('resize', function (e) {
19      setHeaderSkinClassName();
20    });
21    $(window).on('scroll', function () {
22      $('body').removeClass(bodyClassName);
23      if ($('#visitsearch').length) {
24        if ($(window).scrollTop() < 100) {
25          $('body').addClass(bodyClassName);
26        }
27      } else {
28        if ($(window).scrollTop() < 600) {
29          $('body').addClass(bodyClassName);
30        }
31      }
32    });
33  });
34})(jQuery, Drupal, drupalSettings);