text-underline-position:from-font can be used to make an underline clear naskh Arabic descenders

[r12a]

test

Tested with Scheherazade New*, Damascus, Al Nile, Amiri*, Geeza Pro, & Noto Naskh Arabic*.
Note: * Asterisked fonts cannot be tested on Safari unless served as webfonts.

Results:

• Gecko: ✅ None clear the descenders, much less the diacritics. Browser: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:94.0) Gecko/20100101 Firefox/94.0
• Blink: ✅ Only Geeza Pro clears the descenders, but none clear the diacritics. Browser: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/95.0.4638.69 Safari/537.36
• Webkit: ❌ Only Geeza Pro clears the descenders, but none clear the diacritics. Browser: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/15.1 Safari/605.1.15

Results summary