Hi @zitup
I’m sorry to hear that. I doubt you can go back since this is a complete redesign and not just a theme. Personally, I like the new design especially the addition of a dark mode and the always visible in-page navigation. Of course, everything’s a matter of taste in the end. 
If you have some specific problems with the new design you could open issues on the GitHub project for the platform:
If you fundamentally dislike the design I think there’s not much you can do. 
Have a nice day,
Michael