TamperMonkey Script - Youtube always In teather mode.

YT always teather mode

// ==UserScript==
// @name         YouTube Auto Theater Mode
// @namespace    http://tampermonkey.net/
// @version      1.0
// @description  Forces YouTube to always use theater mode
// @author       Ian_Blancasa
// @match        *://www.youtube.com/*
// @grant        none
// ==/UserScript==

(function() {
    'use strict';

    // Function to enable theater mode
    function enableTheaterMode() {
        const theaterModeButton = document.querySelector('.ytp-size-button');
        const isTheaterMode = document.querySelector('ytd-watch-flexy[theater]');

        // If theater mode is not enabled, click the button to enable it
        if (!isTheaterMode && theaterModeButton) {
            theaterModeButton.click();
        }
    }

    // Create a MutationObserver to observe changes in the page (e.g., navigation)
    const observer = new MutationObserver((mutations) => {
        enableTheaterMode();
    });

    // Start observing the body for changes
    observer.observe(document.body, { childList: true, subtree: true });

    // Run the function immediately when the script loads
    enableTheaterMode();
})();