[css-color] Consider exposing native accent color as a system color keyword.

[emilio]

As per #5900 (read that for context), WebKit / Blink already expose it with -webkit-focus-ring-color.

Gecko has these internally as well (-moz-accent-color / -moz-accent-color-foreground).

Depending on how we go about issues like whatwg/html#7993, we might need a standard version of this, but I think that it'd be useful to authors even without it.

[svgeesus]

Does this resolve fully to a color at computed-value time?

[emilio]

Yes, like all other system colors.

[svgeesus]

-moz-accent-color / -moz-accent-color-foreground

Is the proposal for one or two new colors. If one, will it replace both of these?

[emilio]

I think I'd rather have two, since that's what you need to guarantee contrast, otherwise you can't put stuff in the foreground of the accent color.

[fantasai]

So, AccentColor and AccentColorText or SystemAccentColor and SystemAccentColorText? https://www.w3.org/TR/css-color-4/#css-system-colors

[dbaron]

I'd say the first pair, since none of the other system colors start with System.

[svgeesus]

It seems there is agreement, so adding AccentColor and AccentColorText to CSS Color 4

[josepharhar]

I filed a bug to implement this in chrome: https://bugs.chromium.org/p/chromium/issues/detail?id=1338061
What exactly should AccentColorText resolve to in MacOS and windows? I know that in MacOS you can set a specific accent color, but it's just one color. I've yet to implement native accent color stuff for windows in chrome.

[emilio]

@josepharhar In Gecko we use a standard cocoa color: https://searchfox.org/mozilla-central/rev/b1a5802e0f73bfd6d2096e5fefc2b47831a50b2d/widget/cocoa/nsLookAndFeel.mm#135

And on windows we use white or black based on luminance: https://searchfox.org/mozilla-central/rev/b1a5802e0f73bfd6d2096e5fefc2b47831a50b2d/widget/windows/nsLookAndFeel.cpp#737