letter-spacing should take a percentage that scales each individual glyph's advance?

[litherum]

In #5533, we resolved to add advance-override which takes a percentage, which scales up each individual glyph's advance.

Maybe letter-spacing should be able to achieve a similar effect?

[litherum]

Another way of solving this inconsistency would be to change advance-override instead, to accept a grammar that matches letter-spacing.

[fantasai]

Um. I can't imagine anyone wanting tracking that's proportional to the glyph advance width in a proportional font, it would look really messed up for 'm' to have more spacing than 'i', right?

[litherum]

Why should advance-override be different from letter-spacing then?

[fantasai]

@litherum Because it's trying to fake being a different font, not trying to add tracking. Tracking should be added via letter-spacing.