(Aside: “96.61%” is… well, for the type of browser they’re talking about—ones that support such things as CSS and colour—it should be exactly 100%, if not higher. Decide for yourself the sanity of this usage figure.)
CSS Color Module Level 4 <https://www.w3.org/TR/css-color-4/#css-system-colors> revived the concept of system colours, largely fixing the bad aspects and making it all clearly good. Some of the colours are still deprecated, with some at-risk³ dumbing-down. But there are also some new colours: Canvas and CanvasText.
So the problem is that that MDN compatibility data is talking about CSS2 system colours, not CSS Color Module Level 4, which has much lower support (and may not all have been implemented at the same time: most were probably added around 2019, but some in 2021 and AccentColor and AccentColorText in 2022).
Here are the actual colours, to help anyone who wants to update data (have fun identifying when they were added!):
• New in CSS Color Module Level 4: AccentColor, AccentColorText, ActiveText, ButtonBorder, Canvas, CanvasText, Field, FieldText, LinkText, Mark, MarkText, SelectedItem, SelectedItemText, VisitedText.
• Retained from CSS2: ButtonFace, ButtonText, GrayText, Highlight, HighlightText.
¹ Look, some of the system colours were clearly bad, modelling OS styles that were almost completely gone by this time. I suspect that some people didn’t like some of these too-specific values, and they threw the baby out with the bathwater.
² Earlier revisions mentioned the deprecation as being in favour of the ‘appearance’ property, but this was pretty stupid⁴ even when it was prospective, as first written, long before the ‘appearance’ property bit the dust for that time.
³ See <https://www.w3.org/TR/css-color-4/#deprecated-system-colors>: it defines fallback mappings that reduce the variations, but Firefox and Safari haven’t implemented the dumbing-down, still having the more-nuanced stuff they had from decades go. Hence “Results on these 'same as' equivalence tests are not great, which is why the feature is at-risk”.
⁴ No, seriously, just totally clueless and I have no idea what whoever wrote that was thinking, because it was always a completely different thing with only minimal potential overlap in uses.
Its support table is for the CSS2 system colours, as defined back in 1997. <https://www.w3.org/TR/WD-CSS2-971104/ui.html#h-18.2>
(Aside: “96.61%” is… well, for the type of browser they’re talking about—ones that support such things as CSS and colour—it should be exactly 100%, if not higher. Decide for yourself the sanity of this usage figure.)
CSS Color Module Level 3 <https://www.w3.org/TR/css-color-3/#css2-system> then deprecated them, for no good reason¹.²
CSS Color Module Level 4 <https://www.w3.org/TR/css-color-4/#css-system-colors> revived the concept of system colours, largely fixing the bad aspects and making it all clearly good. Some of the colours are still deprecated, with some at-risk³ dumbing-down. But there are also some new colours: Canvas and CanvasText.
So the problem is that that MDN compatibility data is talking about CSS2 system colours, not CSS Color Module Level 4, which has much lower support (and may not all have been implemented at the same time: most were probably added around 2019, but some in 2021 and AccentColor and AccentColorText in 2022).
Here are the actual colours, to help anyone who wants to update data (have fun identifying when they were added!):
• New in CSS Color Module Level 4: AccentColor, AccentColorText, ActiveText, ButtonBorder, Canvas, CanvasText, Field, FieldText, LinkText, Mark, MarkText, SelectedItem, SelectedItemText, VisitedText.
• Retained from CSS2: ButtonFace, ButtonText, GrayText, Highlight, HighlightText.
• Deprecated from CSS2: ActiveBorder, ActiveCaption, AppWorkspace, Background, ButtonHighlight, ButtonShadow, CaptionText, InactiveBorder, InactiveCaption, InactiveCaptionText, InfoBackground, InfoText, Menu, MenuText, Scrollbar, ThreeDDarkShadow, ThreeDFace, ThreeDHighlight, ThreeDLightShadow, ThreeDShadow, Window, WindowFrame, WindowText.
—⁂—
¹ Look, some of the system colours were clearly bad, modelling OS styles that were almost completely gone by this time. I suspect that some people didn’t like some of these too-specific values, and they threw the baby out with the bathwater.
² Earlier revisions mentioned the deprecation as being in favour of the ‘appearance’ property, but this was pretty stupid⁴ even when it was prospective, as first written, long before the ‘appearance’ property bit the dust for that time.
³ See <https://www.w3.org/TR/css-color-4/#deprecated-system-colors>: it defines fallback mappings that reduce the variations, but Firefox and Safari haven’t implemented the dumbing-down, still having the more-nuanced stuff they had from decades go. Hence “Results on these 'same as' equivalence tests are not great, which is why the feature is at-risk”.
⁴ No, seriously, just totally clueless and I have no idea what whoever wrote that was thinking, because it was always a completely different thing with only minimal potential overlap in uses.