[css-values-4] minor quible about informative text in definition of the ic unit

[frivoal]

https://drafts.csswg.org/css-values/#ic

I've reviewed the definition of the ic, and it looks good to me. It closely mirrors the definition of the ch unit, which is as should be, since they're supposed to work very similarly.

That said, I think the terminology in second sentence / paragraph is slightly misleading.

This measurement is an approximation (and in monospace fonts, an exact measure) of a single fullwidth glyph’s advance measure, thus allowing measurements based on an expected glyph count.

The term "monospace font" is typically used to refer to fonts in which the half-width / latin characters are all the same size, and "proportional font" is used to describe those where that's not true. The vast majority of Japanese fonts have full width characters being all the same size (very often 1em), even when the latin part of the font is proportional.

Standard Microsoft fonts provide a good example of the variations out there. "MS Gothic" the classic default Japanese font on widows, is monospaced in the latin range and fullwidth glyphs are the same size. "MS PGothic" is proportional (that's what the P stands for) both in the latin range and in the fullwidth range. Yu Mincho is proportional in the latin range, but all fullwidth glyphs are the same size. See the screenshot below. Mixing proportional latin with equally sized fullwidth glyphs as in Yu Mincho is the more typical design, and such fonts are not usually discribed as monospaced.

I suggest changing the sentence above to something like:

This measurement often an exact measure (and in the few fonts that have variable-size fullwidth glyphs, an approximation) of any single fullwidth glyph’s advance measure, thus allowing measurements based on an expected glyph count.