Sexy Tooltip Using CSS3 (No Images)
http://www.nitinh.com/2010/03/sexy-tooltip-using-css3/
by brasofilo
HTML
<a class="tooltip" tip="This is first tooltip" href="#">Link</a>
CSS
a.tooltip:after{
font:12px/1.4 Arial,Georgia,sans-serif;
content: attr(tip);
display:none;
position:absolute;
padding:5px 10px;
top:0px;
margin:1em 0 3em;
color:#fff;
background:#075698;
left:-20px;
-moz-border-radius:4px;
-webkit-border-radius:4px;
border-radius:4px;
background:-webkit-gradient(linear, left top, left bottom, from(#075698), to(#2e88c4));
background:-moz-linear-gradient(top, #075698, #2e88c4);
background:-o-linear-gradient(top, #075698, #2e88c4);
background:linear-gradient(top, #075698, #2e88c4);
-moz-box-shadow: 0px 0px 4px #000; /* FF3.5+ */
-webkit-box-shadow: 0px 0px 4px #000; /* Saf3.0+, Chrome */
box-shadow: 0px 0px 4px #000; /* Opera 10.5, IE 9.0 */
filter: progid:DXImageTransform.Microsoft.dropshadow(OffX=0px, OffY=0px, Color='#000'); /* IE6,IE7 */
-ms-filter: "progid:DXImageTransform.Microsoft.dropshadow(OffX=0px, OffY=0px, Color='#000')"; /* IE8 */
}
/* creates triangle */
a.tooltip:before{
z-index:13;
position:absolute;
content:"\00a0";
display:none;
width:0;
height:0;
border-style:solid;
top:-3px;
left:0px;
border-width:15px 7px 15px 7px;
border-color:transparent transparent #075698;
}
a.tooltip:hover::before{
display:block;
}
a.tooltip:hover{
z-index:10;
position:relative;
}
a.tooltip:hover::after{
width:200px;
display:block;
margin:25px 0 0 10px;
}