Need a style for listing large chunks of content

[Curtis Hovey]

There are several cases in Launchpad, such as project search and structural subscription rules that are a list of content that is the main content. The pages are hard to read because there is no clear delineation between chunks. This kind of issue is often solved by a listing table that places a rule between content. The picker solves the issue by alternating the shade of the rows. But ther eis no solution for listing that are not tabular.