better-ui

---
name: better-ui
description: Design engineering principles for making interfaces feel polished. Use when building UI components, implementing animations or hover states, or doing any visual detail work. Triggers on UI polish, "feels off", stagger animations, enter animations, theme switch transitions, border radius, optical alignment, image outlines, box shadows, icons, icon stroke weight, motion restraint.
license: MIT
---

# UI polish

Polish comes from a pile of small details that compound. This skill is the reference for which are worth having and what values they take.

When reviewing, slow the interface down. What feels off at 10% speed is what is subtly wrong at full speed.

Keep the project's component library, tokens and density, and match its motion language except where a rule below prescribes an exact interaction.

Every duration, curve, scale and blur below is a specific value, not a range to approximate. `cubic-bezier(0.2, 0, 0, 1)` is not `cubic-bezier(0.4, 0, 0.2, 1)`, and `0.96` is not `0.95`. Use what is written.

Text wrapping, font rendering, tabular numbers and text spacing belong to `better-typography`. Hit areas, focus, keyboard support, ARIA and reduced motion belong to `better-accessibility`. Grouping, section spacing, breakpoints and spatial RTL belong to `better-layout`.

## Concentric border radius

Outer radius = inner radius + padding. Mismatched radii on nested elements is the most common thing that makes an interface feel off. Radius, shadow and outline recipes are in [surfaces.md](surfaces.md).

## Optical over geometric alignment

When geometric centering looks off, align optically. Buttons with icons, play triangles and asymmetric icons all need a manual nudge.

## Shadows for elevation, borders for structure

Where a border exists only to create depth, prefer layered transparent `box-shadow` values. Keep borders that communicate structure or state: dividers, separators and selected or focus states.

## Interruptible animations

Use CSS transitions for interactive state changes, because they can be interrupted mid-animation. Reserve keyframes for staged sequences that run once.

## Split and stagger enter animations

For an infrequent staged entrance where sequence communicates hierarchy, break the content into semantic chunks and stagger them by ~100ms. Animating one container gets you less for the same cost. Leave high-frequency interactions unstaggered. See [enter-exit.md](enter-exit.md).

## Subtle exit animations

Use a small fixed `translateY` rather than full height. Exits should be softer than enters. Use `ease-out` for both directions.

## Contextual icon animations

Animate icons with `opacity`, `scale` and `blur` rather than toggling visibility. Use exactly these values: scale `0.25` to `1`, opacity `0` to `1`, blur `4px` to `0px`.

With a motion library (`motion` or `framer-motion` in `package.json`), match that package's import path, or nearby imports where both exist. Use `transition: { type: "spring", duration: 0.3, bounce: 0 }`. Bounce is always `0`.

Without one, keep both icons in the DOM with one absolutely positioned, and cross-fade with `cubic-bezier(0.2, 0, 0, 1)`. That gives you enter and exit with no dependency. Both recipes are in [icon-transitions.md](icon-transitions.md).

## Image outlines

Give images a `1px` outline at low opacity for consistent depth. Pure black in light mode (`oklch(0 0 0 / 0.1)`), pure white in dark (`oklch(1 0 0 / 0.1)`). Never a near-black like slate or zinc and never a tinted neutral. A tinted outline picks up the surface underneath and reads as dirt on the image edge.

## Scale on press

A `scale(0.96)` on click gives a button tactile feedback. Always `0.96`; anything below `0.95` feels exaggerated. Add a `static` prop to switch it off where motion would distract. See [recipes for CSS, Tailwind and Motion](animations.md#scale-on-press).

## Skip animation on page load

Use `initial={false}` on `AnimatePresence` to keep enter animations off the first render. Check that it leaves intentional page entrances intact.

## Suppress transitions on theme switch

A theme flip changes color, background, border and shadow on nearly every element at once. Every transition on those properties fires together and the switch smears instead of snapping. Inject `*,*::before,*::after{transition:none !important}`, force a reflow, then remove it on the next frame. See the [recipe](animations.md#suppress-transitions-on-theme-switch).

## Transition only what changes

Always name the exact properties: `transition-property: scale, opacity`. Tailwind's `transition-transform` covers `transform, translate, scale, rotate`.

## Use `will-change` sparingly

Only for `transform`, `opacity` and `filter`, which the GPU can composite. Never `will-change: all`. Add it when you see first-frame stutter, not before. See [performance.md](performance.md).

## Match icon stroke to text weight

An icon next to text carries the text's optical weight: `1.5px` stroke beside regular (400) text, `2px` beside semibold (600). One stroke weight per icon set and one icon library per surface. Sizing and RTL flipping are in [icons.md](icons.md).

## One SVG, recolored per state

Icons use `currentColor` and take hover, selected and disabled states from CSS color and opacity, never from separate assets. Outline is the default variant; fill marks the active state.

## Motion restraint

Give high-frequency interactions instant feedback, or a transition of `150ms` or less on opacity and color. A custom animation there charges its attention cost on every trigger.

Every animated state change also needs a static cue: color, an icon, or a label. Motion is never the only feedback channel.

## Before you finish

| Mistake | Fix |
| --- | --- |
| Icons look off-center | Nudge optically with padding, or fix the SVG |
| Jarring staged entrance or exit | Stagger infrequent entrances; keep exits subtle |
| Theme toggle crossfades the whole page | Disable transitions for the swap, force a reflow, restore on the next frame |
| `transition: all` on elements | Specify exact properties |
| First-frame animation stutter | Add `will-change: transform` (sparingly) |
| Hairline icon beside bold text | Match the stroke width to the text weight |

## Reporting

**Severity.** `HIGH` breaks an interaction, makes motion unusable, or leaves a state change visible only while the animation runs. `MEDIUM` is a visible inconsistency in surfaces, icons, or motion. `LOW` is isolated polish.

**Verification.** Without a browser: every state the component defines, meaning hover, focus, active, loading and empty, plus motion durations and easings read from the code. With one: walk each state, and replay motion at 10% speed in the browser's Animations panel. Report every check you could not run as `Not verified`.

**Format.** Group findings under the principle each violates, ordered by severity, one row per root cause listing every location it appears in:

| Severity | Location | Before | After | Why |
| --- | --- | --- | --- | --- |

`Location` is `path/to/file:line`. `Why` names the principle and the user impact.

End with `Block` when any `HIGH` remains, `Approve` otherwise, leaving the rest in the table as work to do. Never `Approve` coverage you did not inspect. With nothing to report, state "No actionable UI-polish findings" and report verification.