The images themselves link to the source of the respective screenshot.
Good Continuation
The left aligned text creates strong vertical lines which group the categories into columns.
Proximity
Two groups appear by clustering related elements closely together and separating the groups as much as possible.
Similarity
Similarity of elements' color and size allows easy recognition of the repeated pattern containing a headline, author, summary, etc.
Uniform Connectedness
White rectangles group elements within "common regions" and simplify the document by allowing the user to inspect a small number of items.