I've come across a few themes in the last week or so where blocks placed in the centre-left or centre-right positions don't take the theme's style.
For example, I have two blocks placed in the centre-right position, one below the other. The uppermost block takes the theme's style correctly whereas the one below it doesn't take any style at all. See my comment/screenshot for the "psair" theme as an example. Let me stress, this theme isn't the only one and themes for other designers do the same thing.
They seems to be the more "complicated" themes using "xo-cancas" type code rather than an old-fashioned theme.html file.
Asny ideas as to what code or class definition(s) are missing?