[css-inline-3] [Meta] Feedback on text-edge and leading-trim

[litherum]

We're filing a series of issues about the design feedback of leading-trim and text-edge. As far as we know, these properties are unimplemented in any browser, which means now is a good time to give feedback on their overall design. For each of the issues we're filing, we don't have a fully-formed proposal that would solve the problem, but we do have some avenues of potential mitigation in mind, and we're offering these ideas as a starting point for further discussion.

Here are the issues we've filed:

• [css-inline-3] leading-trim only has an effect by itself in corner cases #8473
• [css-inline-3] It’s super easy for overflow collisions to occur when using leading-trim #8474
• [css-inline-3] text-edge only has an effect by itself in corner cases #8475
• [css-inline-3] The interaction of text-box-edge with line-height is not predictable by authors #8476
• [css-inline-3] text-edge and line-height have the same conceptual job #8477
• [css-inline-3] text-edge doesn’t allow for fine-tunability (like how line-height does) #8478
• [css-inline-3] It's impossible to use text-box-trim without changing line progression within the paragraph #8829

[dbaron]

Since this is the meta-issue, I figure it might be worth pointing out that these features are rather closely related to my old line-box-contain proposal which is discussed a bit in #3199; there are some other useful links to it in a half-written explainer I wrote (which is on a closely related but still different topic).

[fantasai]

Additional issues related to text-edge and leading-trim:

• [css-inline-3] leading-trim and descendant inlines #3956
• [css-inline-3] text-box-trim accumulation #5426
• [css-inline-3] Naming Stuff #8067 (ongoing bikeshedding discussions)
• [css-inline-3] Negative margins on inline boxes #8182

Also, someone on your team had said months ago they would file an issue about how text-edge should be split so that one controls metrics for line box sizing, and the other controls the metrics for leading-trim; I can't seem to find it, though, but I think it's important.

Also the original issue that introduced the feature, which I've left open because a lot of authors are CCed on it:

• [css-inline] Leading control at start/end of block #3240

And somewhat tangential, but related:

• [css-inline-3] consistent baseline-to-baseline spacing vs line gaps #5564

[fantasai]

Since it came up during today's call, here's a link to the presentation Ethan and I gave at ATypI two years ago on this topic: https://fantasai.inkedblade.net/style/talks/atypi-2021/ (You'll want the MP3 file.) There's also an earlier one, a bit less developed but broader scope, from CSS Day in 2019 at https://www.youtube.com/watch?v=OtlGo48iTOk