.tooltip{width: 200px; color:#000; font: 12px/1.3 Arial; text-decoration:none; text-align:center}
.tooltip span.top{padding: 30px 4px 0; background: url(http://www.credito-vivienda.com/images/bubbletooltips.gif) no-repeat top}
.tooltip b.bottom{padding:3px 4px 10px;color: #548912; background: url(http://www.credito-vivienda.com/images/bubbletooltips.gif) no-repeat bottom}