It seems that CSS class(qa-nav-user-link) of logout link will not be applied if Facebook login plug-in is used.
[Solution example]
qa-plugin/facebook-login/qa-facebook-login.php (L128)
Before: echo '<A HREF="'.qa_html($tourl).'">'.qa_lang_html('main/nav_logout').'</A>';
After: echo '<A class="qa-nav-user-link" HREF="'.qa_html($tourl).'">'.qa_lang_html('main/nav_logout').'</A>';
Best regards.
P.S. to Gideon
Please delete the anonymous post. Sorry...