[csswg-drafts] [css-fonts-5] Should serialization/computed value of `font-size-adjust` include the `ex-height` keyword? (#6442)

jfkthame has just created a new issue for https://github.com/w3c/csswg-drafts:

== [css-fonts-5] Should serialization/computed value of `font-size-adjust` include the `ex-height` keyword? ==
Spec: https://drafts.csswg.org/css-fonts-5/#font-size-adjust-prop

Currently, this says the computed value is:

> the keyword `none`, or a pair of a metric keyword and a `<number>`

However, given that `ex-height` is the default metric to normalize if only a number is specified, when I implemented the keyword+number syntax in Gecko (before this spec text actually appeared), I chose to *omit* the keyword `ex-height` from the `font-size-adjust` serialization, for the sake of backward compatibility.

What do we actually want to do here? Including the metric in all cases is good for consistency and readability, I think, but could possibly be surprising for existing code that operates on `font-size-adjust` based on the original syntax, and expects to see a bare number.

The extended syntax is currently in Nightly, and I am aiming for it to ship in Firefox 92, so it would be good to confirm (sooner rather than later) whether we should change the serialization in our implementation to *include* the `ex-height` keyword. Alternatively, we could modify the spec to say that as the default metric, it should be omitted. Opinions?

Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/6442 using your GitHub account

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Received on Monday, 12 July 2021 15:04:25 UTC