Blur whatsapp chats one sidebar and header

whatsapp_blur.js

// ==UserScript==
// @name         Whatsapp Blur chat
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  Blur the chats sidebar on whatsapp
// @author       Aamir khan
// @match        https://web.whatsapp.com/
// @icon         https://www.google.com/s2/favicons?domain=whatsapp.com
// @grant        none
// ==/UserScript==

(function() {
    'use strict';

    function waitForElm(selector) {
    return new Promise(resolve => {
      if (document.querySelector(selector)) {
        return resolve(document.querySelector(selector));
      }

      const observer = new MutationObserver(mutations => {
        if (document.querySelector(selector)) {
          resolve(document.querySelector(selector));
          observer.disconnect();
        }
      });

      observer.observe(document.body, {
        childList: true,
        subtree: true
      });
    });
  }

   const blur = (x) => el => {el.style.filter = `blur(${x})`};
   const applyBlur = (s, x="1rem") => {waitForElm(s).then(blur(x));}


    applyBlur('#pane-side');
    applyBlur('#main header');

    // Your code here...
})();