An experiment that uses a custom HTML5 data- attribute (data-tooltip) and :before and :after generated content to turn any element into a popup tooltip. No Javascript or extra markup necessary.
As of 21/06/2010, theoretically suitable for consumption in: IE8+, FireFox3.6+, Opera 10+, Chrome 4+ & Safari 4+.
Inspired by Nicolas Gallagher’s article Multiple Backgrounds and Borders with CSS 2.1.