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[css-backgrounds] Specify exact pixel values for border-width: thin, medium, thick #7254
Description
See this Twitter thread: https://twitter.com/tabatkins/status/1522261879762014223
Since browsers agree on 1px, 3px and 5px for border-width: thin, medium, and thick, respectively, it seems to me the spec could require this mapping for all UAs.
Activity
[css-backgrounds] Expect border-width: thin/medium/thick to be 1px/3p…
[css-backgrounds] Expect border-width: thin/medium/thick to be 1px/3p…
tabatkins commentedon May 5, 2022
I suspect the current undefinedness was one of those things where browsers didn't agree when we were nailing down 2.1 and we weren't sure they could agree by our deadline.
fantasai commentedon May 5, 2022
I think it was intentionally left UA-defined, just like the various font-size keywords. My suggestion would be to put “For Web compatibility, it is recommended that these keywords be mapped to 1px, 3px, and 5px, respectively.” or somesuch.
css-meeting-bot commentedon May 11, 2022
The CSS Working Group just discussed
[css-backgrounds] Specify exact pixel values for border-width: thin, medium, thick, and agreed to the following:RESOLVED: thin, medium, and thick will be defined as 1px, 3px, and 5px respectively.The full IRC log of that discussion
<emeyer> Topic: [css-backgrounds] Specify exact pixel values for border-width: thin, medium, thick<emeyer> Github: https://github.com//issues/7254
<emeyer> TabAtkins: Was noticed that we still leave the keyword thicknesses undefined. But all browsers agree on widths at 1px, 3px, 5px.
<emeyer> …Not sure of the exact history, but absent that, the widths are very consistent and don’t see a good reason to leave them undefined.
<astearns> ack fantasai
<emeyer> fantasai: Maybe it was that these were like font-size keywords and left open to interpretation. We should maybe recommend but not require specific widths.
<fantasai> My suggested wording was “For Web compatibility, it is recommended that these keywords be mapped to 1px, 3px, and 5px, respectively.”
<emeyer> TabAtkins: On the other hand, we specify a lot of things that could be adjusted by e-readers. I don’t know that this needs to be left undefined.
<emeyer> …I argue we should go stronger than suggested.
<astearns> ack dbaron
<emeyer> dbaron: This is one of those things that was left up in the air in CSS1, and I don’t remember a proposal to define more precisely. I support the precise definition.
<emeyer> fantasai: If everyone else agrees, that’s fine.
<emeyer> RESOLVED: thin, medium, and thick will be defined as 1px, 3px, and 5px respectively.
[css-backgrounds-3] Defined border-width: thin/medium/thick precisely. …