Last I heard, if there are two different implementations of a feature, the W3C considers it to be a de facto standard. Nor are there any useful distinctions be

Last I heard, if there are two different implementations of a feature, the W3C considers it to be a de facto standard. Nor are there any useful distinctions between "browsers" and "the web". What I suggest is that CSS 4 have the necessary functionality to specify styling of tooltips. It's not that bizarre of an idea. You could set the font, for instance, or colors, or borders. Likely once it becomes a psuedo-element, you could do even fancier things with it. It's a no-brainer.