A dark mode would definitely be nice, but I think there are some larger UI improvements that can be done. Some basic ones would be better padding and spacing for legibility, and making use of the large empty spaces for additional content. And being able to see the number of comments a post has without clicking on it is a must.
I really like this project and the credits system in place. If you're open to the idea I'd be down to collaborate on some of the frontend / design work. Feel free to message me.