Listings are wrapped in a < div > with class "listing". The main < ul > also has class "listing". < li > instances within that list all have classes "listitem" and the class passed in within the list tag - in most cases "normal". They also have a class of either "odd" or "even" to allow styling of alternating entries differently.
Within each entry, everything includes the classes "listitem" and "normal". The title of the event is an < a > with class "title". Other parts are mostly < span > elements with appropriate classes added, eg "when", "location". If the body is included in the listing this is within a < div > (since it contains fairly arbitrary HTML) with class "body".
You can select any particular part of this with an appropriate CSS selector.