.tp {position:relative;text-indent:0;}
.tp b {
   border-bottom:#90f 1px dotted;
   color:#4dc524;
   cursor:help;
   font-weight:normal;
}
.tp b span {display:none;}
/*--  FF, OPERA, IE7 --*/
.tp b:hover {
   border-bottom:red 1px dotted;
   color:red;
}
.tp b:hover span {
   background:#000;
   border:none;
   color:#fff;
   font-size:1.1em;
   display:block;
   padding:17px;
   position:absolute;
   top:-92px;
   left:50%;
   margin-left:-100px;
   z-index:10;
   text-align:left;
   width:200px;
}


.tp strong {
	color:#ffcc66;
}

<!--[if IE 6]>
.tp b {behavior:url(hover.htc);}
.tp .hover {
   border-bottom:red 1px dotted;
   color:red;
}
.tp .hover span {
   background:#000;
   border:none;
   color:#fff;
   font-size:1.1em;
   display:block;
   padding:17px;
   position:absolute;
   top:-92px;
   left:50%;
   margin-left:-100px;
   z-index:10;
   text-align:left;
   width:200px;
}
<![endif]-->