On Fri, Mar 31, 2017 at 1:16 PM, fantasai <fantasai.li...@inkedblade.net> wrote: > On 03/31/2017 07:55 AM, L. David Baron wrote: >> >> On Friday 2017-03-31 12:11 +0800, Tommy Kuo wrote: >>> >>> **Summary** >>> >>> I am intent to implement the property `line-height-step`. And it would be >>> disabled behind the pref `layout.css.line-height-step.enabled` by default. >>> It is a property to make authors create the content with vertical rhythm >>> easier. >>> >>> **Link to standard** >>> >>> CSS Rhythmic Sizing >>> <https://drafts.csswg.org/css-rhythm/> >> >> >> So in the discussions in the working group, I've been somewhat >> skeptical that this feature does a good job of addressing the design >> use cases that it's intended to address. > > > As the co-editor of the spec, I agree with David Baron's concerns. > > Also, based on my discussions with Dave Cramer (CSSWG member who works > in the publishing industry), my understanding is that the the most > common problems are situations that need to be solved with block height > stepping, not line height stepping. An author can fairly easily ensure > that, within a paragraph, the line height follows a strict vertical > rhythm: as long as the text is not interrupted by atomic inline content > or text that has a larger font size / different vertical alignment (and > this covers the majority of text), it will maintain rhythm. But when the > paragraph text is interrupted by different content such as illustrations > and headings, then the rhythm can be thrown off. These are block-level > intrusions into the rhythm, and won't be solved (without hacks like > turning them into inline-blocks) by line height stepping. But they are > solved by block height stepping (which is also outlined in that draft). > > I think we should endeavor to avoid “solutions” that require hacks, so > my advice would be to implement block height stepping first, since it > will more directly solve most of the use cases. I'm less convinced that > line height stepping is necessary; and also there are many issues with > inline layout that need to be addressed before it can be an effective > solution to the problems it addresses. > > * Note that even for headings, which are text, it is the margin-box of > the heading as a whole which needs to fit into the rhythm, not necessarily > each line of it; headings usually have large margins, but the text is set > closely between lines. Similar concerns apply to blockquotes with smaller > text, figures with captions, and other block-level interruptions to prose.
Completely agreed re: the prioritization of block height stepping before line height stepping and the respective design use-cases. The issues noted here, and the summaries of use-cases are worthy of explicitly including in the spec. Perhaps even a coarser change like noting/listing block height stepping *before* line height stepping both in the introduction and structure of the overall document. I'll file spec issues accordingly to discuss separately from this intent to implement thread. Thanks fantasai. Tantek _______________________________________________ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
