Re: [csswg-drafts] [css-values] Cyclic definitions with relative units

The Working Group just discussed `[css-values] Cyclic definitions with relative units`, and agreed to the following resolutions:

* `RESOLVED: define lh unit resolution to be that of the parent when the lh unit is spec on line height or font size`

<details><summary>The full IRC log of that discussion</summary>
&lt;dael> Topic: [css-values] Cyclic definitions with relative units<br>
&lt;dael> github:<br>
&lt;fantasai> fantasai^: Styling the table as all 'display inline' would have no effect on whether these pseudo-classes matched<br>
&lt;dael> florian: There's already a bit of prose that says if you try to use the em usit in font size property or any usit that depends on font size in the font size property we say you fetch from the parent to avoid a loop.<br>
&lt;dael> florian: There was a poorly owrded way to attach this to lh when defining line height. TH emis-phased part meant we still have a problem if trying to do line height in terms of font size.<br>
&lt;dael> florian: What I tried to do is say all font dependant units go to the parent and in addition lh also goes tot he parent if you use it in line height. That breaks the loops.<br>
&lt;dael> florian: We could have a less blunt approach, but I don't think there's use cases for the more subtile variants.<br>
&lt;dael> florian: Precise wording is in the issue.<br>
&lt;dael> fantasai: Works for me.<br>
&lt;dael> myles: I agree we shouldn't be in the business of trying to do a complex dependency analysis.<br>
&lt;dael> Rossen_: I'm waiting for others to have a moment to consider.<br>
&lt;dael> dbaron: The proposal is that lh goes to the parent if used in font size or line height.<br>
&lt;dael> florian: Yes.<br>
&lt;dael> dbaron: Okay.<br>
&lt;dael> ericwilligers: Other things like height?<br>
&lt;dael> florian: No, there's no loop.<br>
&lt;dael> ericwilligers: I know there's no loop, but seems confusing if lh appears 5 times and means 5 different things.<br>
&lt;dael> ??: we have that with ems<br>
&lt;dael> ericwilligers: Don't want to make it worse.<br>
&lt;dael> florian: We need to keep toehr cases working because that's the point of hte lh unit. Only sensible option would be to ban it from line ehight.<br>
&lt;dael> Rossen_: But for the same reason we should have banned em from font.<br>
&lt;dael> florian: And we didn't<br>
&lt;dael> Rossen_: And I think anyone that used em in fonts understands how they did it.<br>
&lt;dael> Rossen_: So, obj to define lh unit resolution to be that of the aprent when the lh unit is spec on line height or font size?<br>
&lt;myles> +1<br>
&lt;dbaron> The cases that go to the parent here are probably cases that can be safely recommended against.<br>
&lt;dael> RESOLVED: define lh unit resolution to be that of the parent when the lh unit is spec on line height or font size<br>
&lt;dael> dbaron: Should the spec have a not saying we suggest not using that behavior? Suggest it's poor practice to use it that way<br>
&lt;dael> myles: Is there one for em?<br>
&lt;dael> dbaron: I don't htink so.<br>
&lt;dael> florian: If we had a plh unit I would say it is, but since we don't I'm not sure it's bad practice.<br>
&lt;dael> Rossen_: I'm fine with either note or no note. If dbaron you feel it's really nec?<br>
&lt;dael> dbaron: I don't. It's just a thought.<br>

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Received on Thursday, 4 January 2018 00:55:39 UTC