.tooltip{
width: 160px; color:#fff ; font-size:0.85em;
font-family: century gothic;
text-decoration:none;text-align:center;
margin-top:8px;}

.tooltip span.top{padding:3px;
    background: url(../img/bt.gif) no-repeat top}

.tooltip b.bottom{ display:none; padding:3px; visibility:hidden;
    background: url(../img/bt.gif) no-repeat bottom}