Puzzles gets a spot line zone where some part of the blue background gets made lighter. This gives a fine finish to the puzzle interface.
However it would be really helpful having that whitish thing away from any interface where one is to read text, because it makes profiles, blogs, puzzle descriptions and such harder to read. Because when one write more text, some of the text will invariable end up in the “spotlight” zone.
Example with text within the marked area getting less clear.