clean up height: 100% styles, add yui3-menu-separator styles
clean up height: 100% styles, add yui3-menu-separator styles

yahoo/pure-site,chensy0203/pure-site,jamesalley/pure-site,weigang992003/pure-css-chinese,pandoraui/pure-site,yahoo/pure-site,jamesalley/pure-site,weigang992003/pure-css-chinese