I see you have moved the categories to he left container and shorted the head picture, good move!!
I think there is still some room for improvements to the user experience. For now there are three equally sized containers.
Widen the center container would: 1. Save on scrolling, 2. Take the focus to the main objective; to enter the discussion..
To 1. There are now only 17 post in the “All Categories” section and already it take more scrolling then some users are willing to oblige themselves to. Widen the center container would shorten at least the text. I’m sure many like myself like the feature to see pictures and read the first bits of the opening Post, but it’s with no question space consuming.
To 2. As an abstract; by using same width containers the forum design appear more like +G or FB, CS already have +G and FB. The user experience on +G/FB is to rather go for a short tweets or just likes than discuss a subject extensively. Using the same format could lead to the same behavior especially by new users, thus it would be counterproductive to your/our visons of the Forum. I know the design reflects on mobile devices but as far as I know these devices would auto format to size.
As for the user experience; different sized containers are much more adaptable by attention then equal sized container in which each container receives the same underlying attention, thus diverting form the intended objective.
The existing forum has build up a sort of own personality, so certainly the “Introduce yourself” category should be added to it once the forum goes live. It’s a very nice touch and builds confidence and interest by new users to be part of an extraordinary experience.