Love this theme — at least on desktop (haven’t tried it on mobile yet). Great job! 
That said…
- The Categories page still feels a bit too old-school and could be better harmonized with the rest of the theme’s design and layout. Maybe something like “category boxes” with rounded corners?
- Also, I’m not a fan of the “new topic” icon. I didn’t like it before, but now it feels even more out of place alongside all the updated visual cues like category, pinned, hot, last changed, etc. I think it deserves something new — and better.