remove stackoverflow sidebars and other junks

sanitize_stackoverflow.user.js

// ==UserScript==
// @name         Sanitize Stackoverflow
// @namespace    https://gist.github.com/scarf005/
// @version      0.2.1
// @description  excesive information is crime
// @author       scarf005
// @match        https://stackoverflow.com/*
// @match        https://*.stackexchange.com/*
// @match        https://askubuntu.com/*
// @match        https://superuser.com/*
// @match        https://serverfault.com/*
// @grant        none
// ==/UserScript==

(() => {
    'use strict'

    // elements to remove
    const clsToRemove = [
        '.top-bar',
        '.left-sidebar', //.ps-relative.js-pinned-left-sidebar.left-sidebar left sidebar
        '.show-votes', // right sidebar
        '.js-dismissable-hero', // asking you to sign up
        '.js-announcement-banner', // something something annoucements
        '.site-footer--container', // footer
        '.bottom-notice', // prompt that asks you to search other questions tagged or post your own
        '.list-reset', // about, products, for teams on nav bar
        '.user-logged-out.h100.list-reset.ai-center.d-flex.-secondary.ml-auto.overflow-x-auto', // login prompt at search bar
        '.post-form.js-add-answer-component', // post your own answer
        '.js-consent-banner', // stackexchange policy banner
        '.s-btn', // buttons that you weren't going to press anyway
    ].flatMap(cls => Array.from(document.querySelectorAll(cls)))

    const tagsToRemove = ['footer']
        .flatMap(t => Array.from(document.getElementsByTagName(t)))

    const totalToRemove = [...clsToRemove, ...tagsToRemove]
    totalToRemove
        .forEach(e => e.remove())

    // fit mainbar to empty spaces
    document.getElementById('mainbar').style.width = 'auto'

})()

Thank you, @scarf005.