So, about that “seem”.
Now we know what
overflow:hidden was for, so that’s a plus!
Anyway, the problem remains: using
line-height: 1.1em and
overflow:hidden you’re essentially instructing the browser to clip tall diacriticals. Using
overflow:visible to overcome this is a hack; the correct way is to set a suitable line-height.
I realized that my own understanding of this issue was lacking, so for my own edification i put together a little file to test this issue. Hopefully it might be of use to others.
I just used a few texts that I happened to have to hand, so this is by no means authoritative. This sample includes Thai, Myanmar, Sinhala, Devanagari, Tibetan, Tamil, Arabic, and Vietnamese.
While there will be some difference across browser and OS, I think the biggest source of variation is in the fonts. They handle these issues very differently, so to be confident, you’d have to use @font-face.
In the cases I have tested, all of these scripts display clipping problems at a line height of 1.1. Setting line-height to a minimum of 1.6 solves this.
Note that using Noto Sans, there is clipping even of the standard Roman descenders at line-height of 1.1.
Here is the HTML file for testing.