It appears the start page is an html document rendered somehow. I know about jWebPane, but its dead and the only other active solution I can find is to embed firefox which is a huge dependency and eats up a ton of memory. Is there any lightweight solution for this?
JEditorPane is the built in Java webpage viewer. It's not a full blown browser but it should do the trick!
The nice part is that it will let you handle link clicks, for instance you could open a screen of you application when the user clicks a link.
CSS seems to be partially supported according to this StackOverflow question/answer