bluemarine & book module

ax made a fix of bluemarine theme. But this fix creare a new problem:
see this postings

The fixed theme and css files (do not know which) makes new problems:
the book-pages do not show up correctly: I noticed that the siblings make this problems
Drupal Handbook
--sibling 1
--sibling 2

and reply by ax

it works properly in Mozilla. i'm not that an css expert - forwarding the issue to Al who did the book css. hopefully, he'll come up with a fix for this.