Good work, everybody. I've already added css to change the color of nodes newer than my last checked flag and css to make a certain monk's trolls less visible.
Update: Thanks eric256!
There is a problem with the replybody class. The actual tag is '<tr class="replybody pmnote-177604"...' (note the space between replybody and pmnote). The space in the class identifier causes issues with both Firefox and IE. The only css workaround that I could find was tr[class="replybody pmnote-177604"], and that is unsupported in IE.
A css expert may have a better solution, but I would ask that the space in the class identifier be removed.