Where can I edit the style for links in postbit? Currently it's styled the same as normal text so it blends in.
Modify a.link, a.link visited and a.link hover a.link active in global.css although the modifications will be applicable for all the links.
That's annoying. I need only postbit links edited.
For that you need some extra css. Or you can wait for other solutions.
Try creating a class ".post_body a:whatever" (you'll need to use the advanced CSS editor).
The post's contents are wrapped in a big <div class="post_body"> and from what I can tell you want to change only the <a>s that are children of the <div>. I'm fairly confident that it will affect all children as well, not just direct children.