.GBicon.book_rightmost { background: url(images/book_rightmost_icon.png) no-repeat; }
.GBicon.book_top { background: url(images/book_top_icon.png) no-repeat; }
.GBicon.book_bottom { background: url(images/book_bottom_icon.png) no-repeat; }
+.GBicon.book_thumb_next { background: url(images/book_thumb_next_icon.png) no-repeat; }
+.GBicon.book_thumb_prev { background: url(images/book_thumb_prev_icon.png) no-repeat; }
.GBicon.play { background: url(images/control_play_icon.png) no-repeat; }