Re: [csswg-drafts] [css-gcpm-3] page group example is incorrect and specificity of nth() is undefined (#3524)

This sounds terribly ungrateful - first, thank you for making the change! But `always` isn't a valid value for `break-before`. See https://drafts.csswg.org/css-break-3/#break-between

You could go for `page-break-before: always`, which is a compatibility option, or `break-before: page` which is the correct value.

However the intention is clear, which is the main thing. So thanks again.

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The specificity of nth() is still undefined (I should have opened a separate issue for this, but as we're here...). I'm almost certain no-one implements this yet (we do but aren't yet public) so you've got no compatibility issues to worry about.

For reference, here's the text from css-page:

> The specificity of page a selector is computed in a manner analogous to the computations defined in the Selectors module:
> 
> Count the number of page type names (= f)
> Count the number of ':first' or ':blank' pseudo-classes (= g)
> Count the number of ':left' or ':right' pseudo-classes (= h)

If you want `@page:nth(1 of name)` to have at least the same specificity as `@page name`, which I think is pretty hard to argue against, then there are exactly three possibilities left:

1. `:nth(1)`, `:nth(2n)` and `:nth(2n + 1)` are all the same specificity as `:first`
2. `:nth(1)`, `:nth(2n)` and `:nth(2n + 1)` are all the same specificity as `:left`
3. `:nth(1)` has the same specificity as `:first`, and `:nth(2n)` has the same specificity as `:left`. `:nth(2n + 1)` has a higher specificity than both of them.

I think option 2 is wrong - this selector should certainly override :left or :right. Between the others I don't really have a strong opinion, except to say that it does need a decision before anyone can implement it with confidence.

(and once decided, I'm more than happy to do a pull request with proposed wording Dave if it will help take the load off you)

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Received on Thursday, 27 February 2020 10:33:46 UTC