A component library tells you which primitive to pick, but it rarely explains the subtle visual decisions that make an interface feel either unpolished or exceptional: why a play icon feels off-center even when mathematically centered, why a nested panel bulges out of its frame, or why a submit button jerks the entire page when loading.
These are Design Cases. Every case documented here targets a recurring visual bug or anti-pattern, paired with a live side-by-side comparison, the underlying perception principle, and the exact code formula to solve it.
How a topic is structured
The unit is a Wrong vs. Right pair:
- ❌ The Anti-Pattern (Wrong) — The implementation reached for first, and the specific flaw it produces: a layout shift, a 1–2px perceptual imbalance, a surface that inverts when the theme changes. Live examples place it on the left.
- ✅ The Best Practice (Right) — The correction together with the mechanism, measurement or formula behind it — geometric centroid against visual mass,
R_inner = max(0, R_outer - gap),min-width: auto— so the fix is understood rather than copied. Live examples place it on the right.
Where the topic is measured against a scale, the scale follows as a table: the type ladder, the radius ladder, the z-index ladder. A case is written against it rather than inventing its own numbers.
The rule about how far a correction reaches belongs to the topic, not to each case, and closes the page where the topic has one — how local an optical adjustment must stay, which layers application code may occupy, what survives prefers-reduced-motion. A boundary that belongs to a single case (tabular-nums is for counters, not prose) sits beside that case as a callout instead.
Design Topics
Explore the micro-craft principles across 8 core design domains: