I prity much like the whole style in general (not a huge fan of dual column) but I'm liking this and I feel it has it's place imo on some areas (speaking if I had dual column). Overall, another excellent looking style, liking the node toggle feature which I knew about but i like that bumping effect the point being the attention to detail throughout is excellent.
The collapse icon however, I think it's too dark (black background red arrow) I would go with something more subtle, like a slightly darker grey and for the arrow a dark grey. Something in the region or thereabouts (for the arrow) #353535.
How do the subforums perform? I noticed that you don't have any on display.
Another minor grievance (perhaps this is by design) the selected tab and hover at the top falls a few pixels short.
Signup/login button in sidebar the border-top seems to have a different coloured border or it might actually be missing.
Node icons I won't mention I'm sure that is on your todo list.
But overall after having a longer look it's shaping up real nice.
Edit: Toggle Icon something like the colouring below. I chop and change my mind regarding colour like the British weather.
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