Re: [csswg-drafts] [css-color][css-color-adjust] We should add sufficient system colors to fully implement the HTML UA stylesheet (#4924)

(This comment was started before @AmeliaBR posted theirs, so by the end I'm mostly just agreeing with them.)

The full list of colors used in the UA stylesheet:

```css
dialog { color: black; background: white; }
dialog::backdrop { background: rgba(0,0,0,0.1); }
:link { color: #0000EE; }
:visited { color: #551A8B; }
:link:active, :visited:active { color: #FF0000; }
mark { background: yellow; color: black; }
table /* lots of variations */ { border-color: black; }
hr { color: gray; }
```

* `dialog { color: black; background: white; }`: Since these are just repeating the assumption of what the main page is already doing, those should be replaceable with `canvas` and `canvastext`.
* `dialog::backdrop { background: rgba(0,0,0,0.1); }`: This one's harder. I doubt we want to provide this color directly. Really, it's just `color-adjust(canvastext alpha(.1))`, so I suppose we can just pretend that exists already? The UA stylesheet already does some "doesn't really exist" stuff anyway.
* `:link`, `:visited`, and `:active`: already done, via `linktext`, `visitedtext`, and `activetext`
* `mark { background: yellow; color: black; }`: probably needs something new; at *least* a new background (`accent`?), probably a full pair (`mark` and `marktext`?)
* `table { border-color: black; }`: should be doable with just `canvastext`
* `hr { color: gray; }`: as @AmeliaBR says, could probably be aligned with button borders, which need their own singular color anyway.

----

So yeah I agree with @AmeliaBR: let's add `mark`, `marktext`, and `buttonborder`. Bikeshedding of `mark` and `marktext` appreciated.

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Received on Monday, 6 April 2020 23:39:39 UTC