Decide what to do with remaining "experimental" CSS features

[rachelandrew]

I've been working through the features marked as experimental in mdn/sprints#2402. It was suggested that those I identified as actually experimental, I created a list of. As discussed in that issue I think it would be better to have a way of marking that there are issues raised against the spec for a feature. The table I have created is as follows, these features are currently still flagged experimental, pending a decision.

Property/Value	MDN Page	Issue
css.at-rules.document	https://developer.mozilla.org/en-US/docs/Web/CSS/@document	postponed to L4. Currently does not appear in any spec. See: https://www.w3.org/TR/2012/WD-css3-conditional-20121213/#changes
css.at-rules.document.regexp	as above	as above
css.properties.appearance	https://developer.mozilla.org/en-US/docs/Web/CSS/appearance	https://drafts.csswg.org/css-ui-4/#appearance-switching
css.properties.background-position-x	https://developer.mozilla.org/en-US/docs/Web/CSS/background-position-x	https://drafts.csswg.org/css-backgrounds-4/#background-position-longhands (only marked as experimental in the data repo, not BCD)
css.properties.background-position-y	https://developer.mozilla.org/en-US/docs/Web/CSS/background-position-y	https://drafts.csswg.org/css-backgrounds-4/#background-position-longhands (only marked as experimental in the data repo, not BCD)
css.properties.break-after.region_context	https://developer.mozilla.org/en-US/docs/Web/CSS/break-after	Regions are themselves in flux, difficult to declare this as stable due to that.
css.properties.break-before.region_context	https://developer.mozilla.org/en-US/docs/Web/CSS/break-before	as above
css.properties.break-inside.region_context	https://developer.mozilla.org/en-US/docs/Web/CSS/break-inside	as above
css.properties.column-width.intrinsic_sizes	https://developer.mozilla.org/en-US/docs/Web/CSS/column-width	https://drafts.csswg.org/css-writing-modes-4/#auto-multicol
css.properties.initial-letter-align	https://developer.mozilla.org/en-US/docs/Web/CSS/initial-letter-align	Potential of renaming: https://drafts.csswg.org/css-inline/#sizing-drop-initials
css.properties.initial-letter	https://developer.mozilla.org/en-US/docs/Web/CSS/initial-letter	Potential of renaming: https://drafts.csswg.org/css-inline/#sizing-drop-initials
css.properties.line-height-step	https://developer.mozilla.org/en-US/docs/Web/CSS/line-height-step	Issue re animation: https://drafts.csswg.org/css-rhythm/#line-height-step
css.properties.max-height	https://developer.mozilla.org/en-US/docs/Web/CSS/max-height	fit-content is defined only as a function, stretch deferred to L4 currently does not have a spec.
css.properties.max-width	https://developer.mozilla.org/en-US/docs/Web/CSS/max-width	as above
css.properties.min-height	https://developer.mozilla.org/en-US/docs/Web/CSS/min-height	as above
css.properties.min-width	https://developer.mozilla.org/en-US/docs/Web/CSS/min-width	as above
css.properties.ruby-align	https://developer.mozilla.org/en-US/docs/Web/CSS/ruby-align	https://drafts.csswg.org/css-ruby/#ruby-align-property
css.properties.ruby-position	https://developer.mozilla.org/en-US/docs/Web/CSS/ruby-position	https://drafts.csswg.org/css-ruby/#rubypos
css.properties.text-align.string	https://developer.mozilla.org/en-US/docs/Web/CSS/text-align	https://drafts.csswg.org/css-text-4/#alignment
css.properties.text-decoration-skip	https://developer.mozilla.org/en-US/docs/Web/CSS/text-decoration-skip	https://drafts.csswg.org/css-text-decor-4/#text-decoration-skip-property
css.properties.text-overflow.fade_function	https://developer.mozilla.org/en-US/docs/Web/CSS/text-overflow	https://drafts.csswg.org/css-text-decor-4/#text-decoration-skip-property
css.properties.text-size-adjust	https://developer.mozilla.org/en-US/docs/Web/CSS/text-size-adjust	https://drafts.csswg.org/css-size-adjust/#adjustment-control
css.selectors.blank	https://developer.mozilla.org/en-US/docs/Web/CSS/:blank	https://drafts.csswg.org/selectors-4/#blank-pseudo (at-risk) see: w3c/csswg-drafts#1967
css.types.attr	https://developer.mozilla.org/en-US/docs/Web/CSS/attr	at-risk in the CR https://drafts.csswg.org/css-values-3/
css.types.image.element	https://developer.mozilla.org/en-US/docs/Web/CSS/image	https://drafts.csswg.org/css-images-4/#element-notation

[Elchi3]

Great research, Rachel! I will dive into this some more, but my first feeling is that we should re-label these as "unstable". It would be a new nomenclature in BCD, but I can see it replacing "experimental". Probably it shouldn't be just a boolean value either, but require an explanatory note.

[rachelandrew]

Yes, I think unstable with a note to explain why would be a good call.

[queengooborg]

I checked through about half of the entries in the list and have found that they are either no longer marked as experimental or have been removed. As such, I'm going to go ahead and close this issue. If I missed any, please feel free to open a new issue and ping me, and I'll happily get it resolved!