Re: [csswg-drafts] [css-scrollbars] What do (semi) transparent colors mean for scrollbar-color (#9853)

The CSS Working Group just discussed `[css-scrollbars] What do (semi) transparent colors mean for scrollbar-color`, and agreed to the following:

* `RESOLVED: transparent colors in the thumb are transparent towards the track, and transparent colors in the track are transparent towards the background; transparency in those colors is not generalized to the entirety of the scrollbar`

<details><summary>The full IRC log of that discussion</summary>
&lt;matthieud> florian: this is abut transparent color for scrollbar-color property<br>
&lt;matthieud> that property takes 2 colors one to the thumb, the other applied to the track<br>
&lt;matthieud> what does transparent means here ?<br>
&lt;matthieud> depend on the operating system, depend between current and older one, they sometimes have design like shaded bottom ...etc...<br>
&lt;matthieud> currently it is not specified how this property affect those other parts<br>
&lt;matthieud> so what do we do with "transparent" (many possible design choices)<br>
&lt;matthieud> in general, browser applies it to the background<br>
&lt;matthieud> we also discovered that some people use entire transparent to make scrollkbar disappear<br>
&lt;matthieud> if it has a bottom(?) what happens.<br>
&lt;matthieud> maybe we need a specific property like scrollbar-transparency or scrollbar-opacity<br>
&lt;miriam> s/bottom(?)/button<br>
&lt;matthieud> even if we only think about the thumb, given a semi transparent color doesnt apply on the whole thing<br>
&lt;matthieud> one way out of it it to be explicit neither the thumb color nor the track color are pre-composed in any way nor ignored<br>
&lt;matthieud> for the use case of making the whole scrollbar transparent we can make a separate property<br>
&lt;matthieud> one important tthing: we need to specify something. right now its the author who is in charge of good contrast<br>
&lt;matthieud> ignoring transparency means black \<br>
&lt;matthieud> if we dont specify the behavior, the author cant ensure good contrast<br>
&lt;matthieud> proposal : there is no magic that apply the transparency of those color to the entiere of the scrollbar<br>
&lt;matthieud> (if we want that, it should be a separate property)<br>
&lt;matthieud> this color has used by UA to shade the various parts<br>
&lt;miriam> +1<br>
&lt;matthieud> the thumb is tranparent toward the track, and the track toward the background<br>
&lt;matthieud> what about pre-composition ?<br>
&lt;florian> s/the thumb is/the colored part of the thumb is<br>
&lt;matthieud> florian: current UA compose toward the background<br>
&lt;matthieud> not transparent toward the potential text on top<br>
&lt;florian> s/toward the background/toward the background, including images and gradients…<br>
&lt;matthieud> astearns: if we resolve to that, is there change to UA necessary ?<br>
&lt;matthieud> florian: not really<br>
&lt;matthieud> when they have flat track/thumb, they already do that<br>
&lt;matthieud> when you have a non flat scrollbar, you cant assume that transparent means disappear scrollbar<br>
&lt;matthieud> however if we go the other way, there might be discontinuity (cf aqua or windows scrollbar)<br>
&lt;matthieud> in an old fashion scorllbar design if you apply a semi transparetn color only to the colored parts, that would make the whole scrollbar disappear : weird<br>
&lt;florian> s/, that would make the whole scrollbar disappear : weird/but apply fully transparent to the whole scrollbar, then there's a discontinuity at very-but-not-fully transparent<br>
&lt;matthieud> whatever we decide today, we are not gonna resolve a new property to control scrollbar opacity today<br>
&lt;matthieud> florian: maybe this is a prerequired to resolve the rest<br>
&lt;matthieud> PROPOSED: we specify what UA are currently doing with transparent color on their flat scrollbar today<br>
&lt;matthieud> the WPT tests are not testing what is in the spec<br>
&lt;matthieud> PROPOSED : we also note that it doesnt mean that all scrollbars will be totally transparent (its true currently, but a coincidence)<br>
&lt;florian> PROPOSED: transparent colors in the thumb are transparent towards the track, and transparent colors in the track are transparent towards the background; transparency in those colors is not generalized to the entirety of the scrollbar<br>
&lt;matthieud> note that we might need to define precisely what "background" means here ?<br>
&lt;astearns> RESOLVED: transparent colors in the thumb are transparent towards the track, and transparent colors in the track are transparent towards the background; transparency in those colors is not generalized to the entirety of the scrollbar<br>
&lt;fantasai> some discussion about how UAs paint over the background directly, not over e.g. text content underneath<br>
&lt;matthieud> florian: non flat scrollbar already exist on Linux<br>
&lt;florian> s/exist on Linux/exist on at least Linux<br>
</details>


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Received on Thursday, 4 July 2024 00:01:39 UTC