text-combine-upright:all will make up to 4 characters run horizontally in vertical text, and not exceed the line width.

[r12a]

Test link(s):

text-combine-upright:all

Results:

• Gecko: ✅ Browser: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:94.0) Gecko/20100101 Firefox/94.0
• Blink: ✅ _Browser: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_157) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/95.0.4638.69 Safari/537.36
• Webkit: ✅ _Browser: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_157) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/16.5.2 Safari/605.1.15

Related tests: Vertical text