modern browsers don't need javascript for tooltips. js for legacy is easy enough

no javascript tooltips.css

/**************************
BEGIN TOOL TIP CSS
**************************/
a.tip {position: relative;}
a span.tip-content,
a span.tip-bottom {
	position: absolute;
	width: 273px;
	padding: 20px 50px 5px 20px;
	bottom: 48px;
	left: -50px;
	background: transparent url(images/tool-tips-content.png) no-repeat 0 0;
	color: #6a645c;
	}
	a span.tip-bottom {
		display: block;
		padding: 0 20px;
		bottom: 16px;
		height: 33px;
		background: transparent url(images/tool-tips-bottom.png) 0 0 no-repeat;
		}
		.tip-content strong {
			display: block;
			border-bottom: 1px dotted #c1c1c1;
			font: bold 12px Georgia;
			padding-bottom: 3px;
			margin-bottom: 5px;
			}
		.tip-content em {
			text-decoration: underline;
			font-style: normal;
			color: #5683ae;
			padding-right: 14px;
			background: transparent url(images/arrow.png) no-repeat right 2px;
			}
		.tip-content img {
			float: left;
			margin-right: 5px;
			}
/*************************************
ADDITIONAL CSS FOR NON JAVASCRIPT USE
**************************************/
a span.tip-content,
a span.tip-bottom {visibility: hidden;}

a:hover span.tip-content,
a:hover span.tip-bottom {visibility: visible;}