MediaWiki:Vector.js

var button = document.createElement("button");
button.innerHTML = "Сменить тему";
button.className = "theme-button";
button.onclick = toggleTheme;

var container = document.getElementById("p-personal");
if (container) {
    container.parentNode.insertBefore(button, container);
}

window.onload = function() {
    var random = Math.random();
    var isLightTheme = localStorage.getItem("isLightTheme");
    if (isLightTheme === "true") {
        document.documentElement.classList.add('light');
    }
};

function toggleTheme() {
    var isLightTheme = document.documentElement.classList.toggle('light');
    localStorage.setItem("isLightTheme", isLightTheme);
}