Hello webkit-dev, I would like to request an official position on the HTML spec change described in this pull request: https://github.com/whatwg/html/pull/5894/files Together with https://github.com/whatwg/html/pull/6032, this means that width/height attributes on a <source> element inside a <picture> will get mapped to CSS properties width/height/aspect-ratio on the <img> in the <picture>. Thanks, Christian