Rhythm is the premium signal
Users cannot name spacing, but they feel it instantly. A page where padding jumps between 8 and 23 pixels reads as cheap regardless of the design; one where everything lands on a 4 or 8px grid reads as deliberate. Consistency is the entire trick.
Define five spacing steps — 4, 8, 12, 16, 24 — and refuse to invent new ones. Every gap, padding, and margin picks from the set.
Columns are for meaning
A two-column grid is not a layout, it is a constraint. Assign the columns meaning: primary content at 2/3, meta at 1/3, or a 12-column grid for cards. The rule that matters is that nothing straddles columns unless it is a section break.
The practical test: vertical rules are invisible, horizontal rules are everywhere. Align baselines, not just edges.
The hover one-pixel
Card hovers translate one pixel and lift a shadow. That one pixel is the difference between a page that feels alive and one that feels static — and it costs nothing.
Pair it with border-color shift on hover. Two state changes, both cheap, both expected.