Re: [csswg-drafts] [css-borders] Add a 'hairline' border-width value (#3720)

Okay, I understand your concerns, Florian, but seem to disagree on the harm that authors could actually cause themselves. As you say, a hairline width is less likely to be a problem than a dppx width. People *can* do stupid things, but it's not meaningfully different from manually specifying a `.1px` or something, which they can do today (and don't).

So my preference is to accept [Emilio's "ideal proposal"](https://github.com/w3c/csswg-drafts/issues/3720#issuecomment-3762832472), that is:

* add `hairline` to `<line-width>`
* add `env(hairline)` to give the same width but generically
* add `border` as a rounding method to `round()` to solve some of the "just act like a border" use-cases that aren't necessarily hairline-related; that is, `round(border, Xpx)`

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Received on Wednesday, 4 March 2026 17:34:56 UTC