title: How to make about:newtab (new tab page) in dark mode while dark mode activated in firefox 69+
body: <p>I've firefox 69,
  newtab page stays light while dark mode activated.</p>
  
  <p>I activated dark mode via <code>about:config?filter=browser.in-content.dark-mode</code> (changed to <code>true</code>)
  but <code>about:home</code> / <code>about:newtab</code> stays light</p>