I made the background darker, so that the content area is more visible by comparison. I'm not sure about making the reds any brighter as red-on-black can cause eye strain. Happy to tweak the values a bit until we can settle on a nice readable color.
One more change is to maybe make the thread bodies a bit wider, since right now it feels a little constrained as there isn't much used space. I used to use forum themes for MyBB and XenForo and there was a body width option, maybe check if this theme has one?