Page media has been supported for decades. Line numbers aren’t strictly related to page media. It’s hard to complain about the lack of in-depth support for a media that isn’t meant to display “the web”.
I do agree that it could be better. They have been adding print-related features though, at least I remember some in CSS3. CSS Colors Level 4 includes cmyk functions.
I do agree that it could be better. They have been adding print-related features though, at least I remember some in CSS3. CSS Colors Level 4 includes cmyk functions.