I've never had any problem using Craig's List and it just works. There are no hamburgers, no material design, the dropdowns look like dropdowns, and the links look like links. I love Craig's List! It's one of the only shopping/marketplace websites I don't dislike.

My philosophy is that if you want it to have fancy CSS and skeuomorphic buttons, use a CSS extension and make your own CSS for it. Even better - use a browser that lets you edit a page's CSS in WYSIWYG (if there are any).

If Craig's List was suddenly revamped and looked like Amazon or Newegg, I would no longer use it.