We are going to be changing many of the class names used by the Widget in the next major version (0.5.0), which will hopefully be out in the next few days.
I wanted to be able to give those that see this a little heads up (It is also mentioned in the current versions changelog) and to serve as an explanation to users who have problems.
Why are we doing this?
There has been significant feedback from users who's theme styles have effected (broken) the styling of our Widget. This is because we use standard, common and descriptive class names (like .header, .meta, .reply, etc).
Isn't there another option?
The other option is to specify all possible rules for each of the elements we use, this would create much more CSS and make viewing our CSS and creating your own custom rules much more difficult.
While we are still early in the plugins life we want to take this opportunity now, so that we do not get stuck in the position where changing the classes could potentially break thousands of sites.
I hope those that this change effects will understand the reasons behind it. Sorry for any inconvenience caused.