Users can use a browser plugin like Stylish to do this themselves if they desire. Of course, I'm sure it's fairly trivial to make a plugin that would do this.
Well, In the homepage it would be cool if we can drag all the little Topics around to our liking. Like the ones we favorite we drag to the top. And the ones we dont visit often we drag to the bottom I think this would be a great feature to have in NodeBB.
Add a "Edit Homepage" button. So there wont be issues with mobile Users!
What theme is that? Lavender with the post previews disabled?
I'm not sure about if this is something I'd implement personally, but if users wanted to keep the layout of their categories, it would have to be stored in the DB - assuming they wanted the categories to remain semi-sorted to their original design when accessing from a mobile device.
This would just involve a change in masonry to something else. Maybe mixitip.