docs/docs/resources/js/mermaid_dark_light_switcher.js

var paletteSwitcher1 = document.getElementById("__palette_1");
var paletteSwitcher2 = document.getElementById("__palette_2");

paletteSwitcher1.addEventListener("change", function () {
    location.reload();
});

paletteSwitcher2.addEventListener("change", function () {
    location.reload();
});