[csswg-drafts] [css-overflow-4] effect of gutters on viewport units (#5254)

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

== [css-overflow-4] effect of gutters on viewport units ==
https://drafts.csswg.org/css-values/#viewport-relative-lengths says:

> The viewport-percentage lengths are relative to the size of the initial containing block. When the height or width of the initial containing block is changed, they are scaled accordingly. **However, when the value of overflow on the root element is auto, any scroll bars are assumed not to exist.**

This is fine if we have overlay scrollbars, and `scrollbar-gutter` is `auto` or `stable`, since no space is consumed for the scrollbar anyway.

This seems regrettable, but probably unavoidable, if we have classic scrollbars and `scrollbar-gutter` is `auto`, since the presence or absence of scrollbars will depend on layout, and having the viewport units depend on layout is problematic.

However, if we have classic scrollbars and `scrollbar-gutter` is `stable` (or `always`, which does the same thing in the case of classic scrollbars), it would seem much preferable for the viewport percentage units to be relative to the ICB as reduced by the always-present gutter.

For overlay scrollbars with an`always` `scrollbar-gutter`, I suspect it should they should also be relative to the ICB as reduced by the always-present gutter, but I am less sure, and the answer might depend on the resolution to https://github.com/w3c/csswg-drafts/issues/5253.

Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/5254 using your GitHub account

Received on Tuesday, 23 June 2020 09:13:24 UTC