[csswg-drafts] [css-position] Define that containing block for fixed positioning is generated by the padding area

Loirooriol has just created a new issue for https://github.com/w3c/csswg-drafts:

== [css-position] Define that containing block for fixed positioning is generated by the padding area ==
https://drafts.csswg.org/css-position-3/#def-cb just says

> If the element has position: fixed, the containing block is established by the viewport in the case of continuous media or the page area in the case of paged media. 

However, the containing block can also be generated by an ancestor element e.g. with `transform: scale(1)`.

In this case, the spec needs to define which area of the element (border area, padding area, content area) is used for generating the containing block.

Firefox, Chromium and WebKit(*) use the padding area, just like with absolute positioning. The spec should define this.

(*) WebKit uses the padding area for rendering, but the border area for `getComputedStyle`, https://bugs.webkit.org/show_bug.cgi?id=189518

Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/3097 using your GitHub account

Received on Tuesday, 11 September 2018 20:48:31 UTC