Better support for illegal-example

[darobin]

These are not handled completely well — they should cause an additional "illegal" class to be added to the container, and styled accordingly.

[marcoscaceres]

Do you have an example spec that makes use of this? Maybe a few more details about the kind of styling you would expect to see?

[darobin]

Illegal examples should be styled differently from legal ones. I think this is mostly a CSS improvement.

[marcoscaceres]

Moved to TR style project instead.