Fall back to alternative fonts when characters are not available in Dr

[andymatuschak]

Dr does not include Chinese characters (or extended character sets associated with many other languages). We should fall back reasonably in this case, e.g. font-family: Dr, Futura, sans-serif

[L-M-Sherlock]

Now I know the visual problem in Orbit if I use it with Chinese text. The line spacing is too narrow for most Chinese:

For example, you can see the Chinese documents on apple.com: 用于 Mac 的Pages: 在 Pages 文稿中设定行间距和段落间距

Line height between 1.5 to 2.0em would be more legible than the current.

[andymatuschak]

Aha, thanks for explaining. Yes, I see: the Chinese characters occupy the full ascender and descender bounding box. This is apparently a common problem, and difficult to handle correctly. https://stackoverflow.com/questions/28947430/is-line-height-determined-by-the-first-font-in-a-css-font-stack

Probably the most natural way to fix this would be to add a Markdown parsing stage which emits special <span>s for affected characters when they're encountered. Hm…