.sub_nav_container_documentation {
  display: block;
}
a.navisub_link_manual {
   background: url(../but/manual_selected_sub.png) no-repeat;
}
a.navisub_link_manual:hover {
   background: url(../but/manual_selected_sub.png) no-repeat;
}
.sub_nav_container_documentation {
  display: block;
}
a.navimain_link_documentation {
   background: url(../but/documentation_selected.png) no-repeat;
}
a.navimain_link_documentation:hover {
   background: url(../but/documentation_selected.png) no-repeat;
}