The CSS WG has published a First Public Working Draft of the CSS Scoping Module Level 1:
http://www.w3.org/TR/css-scoping-1/ This specification defines various scoping/encapsulation mechanisms for CSS, including scoped styles and the @scope rule, Shadow DOM selectors, and page/region-based styling. It is an early-stage working draft, and the features described therein are not well-baked and may change dramatically or be removed. The CSSWG encourages comments on both design and details of these features. Please send any comments to this mailing list, <www-st...@w3.org>, and please, prefix the subject line with [css-scoping] (as I did on this message). For the CSS WG, ~fantasai