GitHub Gist apply dark theme on secret Gists

github-gist-apply-dark-theme-on-secret-gists.user.js

// ==UserScript==
// @name         GitHub Gist apply dark theme on secret Gists
// @namespace    https://github.com/benok/
// @description  Apply dark theme to your secret Gists on GitHub Gist
// @include      https://gist.github.com/*
// @version      2022.11.30.1
// @homepage     https://gist.github.com/benok/69b98fc38aa5884234fe50326ef014ae
// @downloadURL  https://gist.github.com/benok/69b98fc38aa5884234fe50326ef014ae/raw/github-gist-apply-dark-theme-on-secret-gists.user.js
// @author       benok
// @grant        none
// @license      MIT
// ==/UserScript==

(function() {
    'use strict';
     if ( (document.querySelector('span.Label.v-align-middle')||
           document.querySelector('span.Label.Label--secondary')/* Editing page */).textContent.includes('Secret')) {
         console.log('secret gist. set data-color-mode to dark');
         document.querySelector('html').setAttribute('data-color-mode', 'dark');
    } else {
         console.log('public gist. set data-color-mode to light');
         document.querySelector('html').setAttribute('data-color-mode', 'light');
    }
})();

I'm not that good with JavaScript, so I'd be happy if you could fork this and implement support for the "All gists" tab!
(Please see also private repo version.)

Having trouble now.
Setting html's data-color-mode doesn't update the actual page theme. :-(
(Setting the default theme to dark, it works partially, but unstable. May be needed to change apply timing.)