W3C Invites Implementations of CSS Containment and Flexible Box Layout Module Level 1

The CSS Working Group invites implementations of two updated Candidate Recommendations:

• CSS Containment Module Level 1 describes the 'contain' property, which indicates that the element’s subtree is independent of the rest of the page. This enables heavy optimizations by user agents when used well.
• CSS Flexible Box Layout Module Level 1 describes a CSS box model optimized for user interface design. In the flex layout model, the children of a flex container can be laid out in any direction, and can “flex” their sizes, either growing to fill unused space or shrinking to avoid overflowing the parent. Both horizontal and vertical alignment of the children can be easily manipulated. Nesting of these boxes (horizontal inside vertical, or vertical inside horizontal) can be used to build layouts in two dimensions.

CSS is a language for describing the rendering of structured documents (such as HTML and XML) on screen, on paper, etc.