.rtop
{
    display: none;
}
.rbottom
{
    display: none;
}

/*
http://www.html.it/articoli/nifty/index.html

For Css issues in Fire Fox please refer below links
http://www.complexspiral.com/publications/containing-floats/
http://www.positioniseverything.net/easyclearing.html
http://forums.digitalpoint.com/showthread.php?t=82168
Tips and Trics for FFox
http://www.mozilla.org/support/firefox/tips
http://www.cssplay.co.uk/menus/drop_examples.html
*/