FYI:
We're playing with the idea of icons per forum at the moment and changed out the 'no new posts in this topic' icon from the plain vanilla to a topic-related icon to see what they could look like. We're aware that we have not changed the 'new posts' and 40 or so sub-variants of the icon, but it's easier to change just 1 to see how it looks, so don't worry if everything is not yet consistent as it's not yet meant to be!
Experiment ends tomorrow, so they'll disappear. General feedback is positive but we need to deliver a coherently styled group of icons (and obviously a complete suite of them) which will require some additional work if we implement them!