I use the Timeless theme myself (https://en.wikipedia.org/wiki/Pangolin?useskin=timeless). If you like the Timeless theme’s less-busy navigation but don’t like that theme’s sticky header and misaligned icons, you can copy my CSS customizations for it: https://en.wikipedia.org/wiki/User:Rory_O%27Kane/timeless.cs...

To try those customizations yourself, copy the CSS code on that page. Then, in your Wikipedia account’s Preferences > Appearance (https://en.wikipedia.org/wiki/Special:Preferences#mw-prefsec...), choose Timeless as your skin. Finally, click Custom CSS next to Timeless, paste my CSS, and click Save. If you don’t like those customizations, just edit the page again and delete the CSS.

I made one final tweak to the Timeless theme: on page load, a bit of JavaScript scrolls the page down to hide the search bar and user menu. Most of the time I don’t care about that part of the page when I visit an article, and when I do want to see it care, I just have to remember to scroll up.

I installed that JavaScript using a custom user script installed with https://violentmonkey.github.io/, though you could probably get it working with the Custom JavaScript link in your Preferences > Appearance settings too. Here’s a simplified version of my JS that you are free to copy:

  // ==UserScript==
  // @name Wikipedia – scroll below Timeless-skin static header on load
  // @description When using Wikipedia’s Timeless skin, modified with user CSS to not have a fixed header, this scrolls below that header when a page loads. This hides the distracting color bar and lets you see more of the article. If you want to see the header, just scroll back up.
  // @namespace roryokane.com
  // @match https://en.wikipedia.org/wiki/*
  // @grant none
  // @author Rory O’Kane
  // ==/UserScript==
  
  const headerHeight = 60;
  
  const usingTimelessSkin = () => document.body.classList.contains("skin-timeless");
  
  if (window.___location.hash === "" && usingTimelessSkin()) {
    window.scrollTo(0, headerHeight);
  }