https://www.nepomuk.cz/bundles/kalendar/js/calendarFunc.js?v=v6.5.0c

1calendarFunc = {
2    getOther: function (month, year, targetID, imported, noLongActions, columnId, widgetId, lang) {
3        jQuery.post(
4            '/modules/kalendar/ax_calendar_mp.php',
5            {
6                month: month,
7                year: year,
8                imported: imported,
9                nla: noLongActions,
10                cid: columnId,
11                wid: widgetId,
12                lang: lang,
13            },
14            function (returnData) {
15                jQuery('#' + targetID).replaceWith(returnData);
16                dropdownColor();
17            },
18        );
19    },
20};
21
22function dropdownColor() {
23    const sourceElementBackground = document.querySelector('.calendar .month.action:not(.today)');
24    const sourceElementColor = document.querySelector('.calendar .month.action:not(.today) .day-action');
25
26    if (sourceElementColor) {
27        const sourceColor = getComputedStyle(sourceElementColor).color;
28        const sourceBackgroundColor = getComputedStyle(sourceElementBackground).backgroundColor;
29
30        if (sourceColor) {
31            document.querySelectorAll('.calendar .calendar-dropdown-menu .dropdown-item').forEach((item) => {
32                item.style.color = sourceColor;
33            });
34            document.querySelectorAll('.calendar .calendar-dropdown-menu ').forEach((item) => {
35                item.style.backgroundColor = sourceBackgroundColor;
36            });
37        }
38    }
39}
40
41document.addEventListener('DOMContentLoaded', dropdownColor);