Systems
The "no-line" rule and what replaces it
Removing 1px borders forces every layout decision to be honest. Tonal stacking, surface deltas, and the case against decorative lines.
Lines hide weak hierarchy. Remove them and the layout has to stand on its own structural decisions.
In their place: tonal stacking, surface deltas, and a small set of typographic eyebrows that mark sections without borrowing visual weight from a divider.