If you use https-everywhere, you can just make a custom rule -- click "Add a rule for this site" in the extension popup and fill this in:

  Matching regex
  ^https://www\.reddit\.com/
  Redirect to
  https://old.reddit.com/

What does adding "old" do?

Disables their recent redesign and reduces the amount of javascript and bullshit that comes with the update.

You'll get the 'old' design. Check with your "private mode" browser :

- https://www.reddit.com/ - https://old.reddit.com/

Interesting those have not only different designs but also different stories for me. I prefer the old one.

Shows post using the older site design I believe.