4 ms·

> “monospace fonts tend to be wider, so the default font size (medium) is scaled so that they have similar widths” > “the base size depends on the font family

> “monospace fonts tend to be wider, so the default font size (medium) is scaled so that they have similar widths” > “the base size depends on the font family and the language … Default system fonts are often really ugly for non-Latin- using scripts.” ‘often’, ‘tend to be’: I am worried. I think it’s a really bad idea to deflect default behavior based on such assumptions, certainly when the deviations are a blind process triggered by proxies (like language tags and some vaguely statistical rules-of-thumb for dealing with generic font family names). That is: without even looking at the actual design and metrics of the actual font involved.¹ What happens if the monospaced font in case has a normal x-height and/or an advance-width equal to that of its serif counterpart? What if the CJK and Devanagari fonts have characters drawn already ‘big on the body’?² Then such hard-coded default moonshot-fixes which try to cater for the lowest common denominator will make things needlessly hard to debug and force the designer still to ad-hoc size-adjust font per font, but now also trying to fix the browser’s ‘fixes’. (Too bad: any `normalize.css` wont help…³) And yet, all of the needed data is available in the font file. There’s even a dedicated CSS property for dealing with fonts’ varying metrics: `font-size-adjust`.⁴ Not that browser makers care to implement⁵, but since the OP’s post concerns Firefox (which does support `font-size-adjust`, but the article does not discuss it) I wonder: is it a matter of performance that retrieving the actual font metadata and metrics is left out of the equation? Surely, the fact that local font files, base64 data-URI embedded or externally hosted ones can be used, makes implementation all but trivial… At Textus.io⁶ we’re going great lengths to solve typographic issues such as these. Point in case: for each font we read out the `xHeight` value, then calculate the actual font-size relative to the font’s UPM (unitsPerEm), so we have consistent apparent font-sizes, c.q. aspect ratios. I think it all boils down to a separation of concerns: proportion and interrelated sizes (ascender, caps, descender, x heights, stem width, etc.) are up to the discretion of the font designer, overall aspect size is the business of the typesetter (css stylesheet author), and the browser ought always draw consistently, regardless of generic font family name, language and/or Unicode code range. ¹ https://opentype.js.org/font-inspector.html https://opentype.js.org/font-inspector.html ² https://medium.com/@xtianmiller/your-body-text-is-too-small-5e02d36dc902 https://medium.com/@xtianmiller/your-body-text-is-too-small-... ³ https://github.com/h5bp/html5-boilerplate/issues/724 https://github.com/h5bp/html5-boilerplate/issues/724 ⁴ https://developer.mozilla.org/en/docs/Web/CSS/font-size-adjust https://developer.mozilla.org/en/docs/Web/CSS/font-size-adju... ⁵ http://caniuse.com/#feat=font-size-adjust http://caniuse.com/#feat=font-size-adjust ⁶ http://www.textus.io http://www.textus.io

chrismorgan 9y ago
I believe I’ve come across allegations that the metrics encoded in the font (xHeight and unitsPerEm, by the sound of it) are fairly hit-and-miss. Any comments on that? Bear in mind non-Latin scripts also.
- rhythmvs 9y ago
  Sure. Badly produced fonts (those you can find on the cheap), tend to have faulty metrics: i.e. the designer did not change the default ones of the font design app (Glyphs, FontLab, FontForge, &c.) they are using so as to match the actual outlines of the glyphs they drew. E.g. the font’s metrics tell: xHeight=500 and UPM=1024, so we may assume the aspect ratio is 0.48. But then we look at the outlines and see the designer drew the upper most top node of the x at the 600 coordinate on the Y-axis. So, in fact, the actual aspect ratio is 0.59, and thus the metrics are useless indeed… But again: should we then _assume_ to be always dealing with badly produced fonts? Or could we just expect font metrics to tell the truth? For if we won’t, then we’re totally lost, and will make things even worse for professionally produced fonts, which do honor the specs. (As for non-Latin scripts: it’s indeed up to the discretion of the font designer how to draw the height of, say, CJK characters or the size of the teeth in Arabic, but always _relative to the xHeight_ as stated in the font’s metadata, so the font behaves consistent with the specs.) At Textus.io, we therefor rely on the font’s built-in metrics metadata, for now. But since we are obsessed with fool-proof typography, we are indeed considering to look at the actual coordinates of the outlines instead… I do not expect browsers to do deal with inconsistent font metrics, though. As a developer, I instead want to rely on browsers behaving consistent, being assured they won’t ‘fix’ things I already fixed, for then the outcome will be totally unpredictable. That’s why we have standards and specs after all, haven’t we?
  - irishsultan 9y ago
    Note that these are mostly user configurable settings (although it's only the default font size that can be configured, not the other absolute and relative values)
  - Manishearth 9y ago

chrismorgan 9y ago

I believe I’ve come across allegations that the metrics encoded in the font (xHeight and unitsPerEm, by the sound of it) are fairly hit-and-miss. Any comments on that? Bear in mind non-Latin scripts also.

rhythmvs 9y ago
Sure. Badly produced fonts (those you can find on the cheap), tend to have faulty metrics: i.e. the designer did not change the default ones of the font design app (Glyphs, FontLab, FontForge, &c.) they are using so as to match the actual outlines of the glyphs they drew. E.g. the font’s metrics tell: xHeight=500 and UPM=1024, so we may assume the aspect ratio is 0.48. But then we look at the outlines and see the designer drew the upper most top node of the x at the 600 coordinate on the Y-axis. So, in fact, the actual aspect ratio is 0.59, and thus the metrics are useless indeed… But again: should we then _assume_ to be always dealing with badly produced fonts? Or could we just expect font metrics to tell the truth? For if we won’t, then we’re totally lost, and will make things even worse for professionally produced fonts, which do honor the specs. (As for non-Latin scripts: it’s indeed up to the discretion of the font designer how to draw the height of, say, CJK characters or the size of the teeth in Arabic, but always _relative to the xHeight_ as stated in the font’s metadata, so the font behaves consistent with the specs.) At Textus.io, we therefor rely on the font’s built-in metrics metadata, for now. But since we are obsessed with fool-proof typography, we are indeed considering to look at the actual coordinates of the outlines instead… I do not expect browsers to do deal with inconsistent font metrics, though. As a developer, I instead want to rely on browsers behaving consistent, being assured they won’t ‘fix’ things I already fixed, for then the outcome will be totally unpredictable. That’s why we have standards and specs after all, haven’t we?
- irishsultan 9y ago
  Note that these are mostly user configurable settings (although it's only the default font size that can be configured, not the other absolute and relative values)
- Manishearth 9y ago