make-interfaces-feel-better

---
name: make-interfaces-feel-better
description: >-
license: MIT
---

# Details that make interfaces feel better

Great interfaces rarely come from a single thing. It's usually a collection of small details that compound into a great experience. Apply these principles when building or reviewing UI code. Before suggesting or writing a fix, identify the project's existing styling system and express the change in that system: Tailwind in a Tailwind project, plain CSS in a CSS project, or the established CSS-in-JS approach. Never introduce a second styling system just to apply a polish fix.

When reviewing, slow the interface down: replay motion at 10% speed in the browser's Animations panel and walk every state: hover, focus, active, loading, empty. What feels off at 10% speed is what's subtly wrong at full speed.

## Quick Reference

| Category | When to Use |
| --- | --- |
| [Typography](typography.md) | Text wrapping, font smoothing, tabular numbers |
| [Surfaces](surfaces.md) | Border radius, optical alignment, shadows, image outlines, hit areas |
| [Animations](animations.md) | Interruptible animations, enter/exit transitions, icon animations, scale on press, motion restraint |
| [Icons](icons.md) | Icon stroke weight, states via `currentColor`, outline vs fill, sizing, RTL flipping |
| [Performance](performance.md) | Transition specificity, `will-change` usage |

## Core Principles

### 1. Concentric Border Radius

Outer radius = inner radius + padding. Mismatched radii on nested elements is the most common thing that makes interfaces feel off.

### 2. Optical Over Geometric Alignment

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

### 3. Shadows for Elevation, Borders for Structure

For buttons, cards, and containers whose border exists only to create depth, prefer layered transparent `box-shadow` values. Keep borders that communicate structure or state: dividers, layout separators, and selected or focus states.

### 4. Interruptible Animations

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

### 5. Split and Stagger Enter Animations

For an infrequent staged entrance where sequence helps communicate hierarchy, break content into semantic chunks and stagger them by ~100ms instead of animating one container. Do not stagger routine, high-frequency interactions.

### 6. Subtle Exit Animations

Use a small fixed `translateY` instead of full height. Exits should be softer than enters. Use `ease-out` for both enter and exit transitions.

### 7. Contextual Icon Animations

Animate icons with `opacity`, `scale`, and `blur` instead of toggling visibility. Use exactly these values: scale from `0.25` to `1`, opacity from `0` to `1`, blur from `4px` to `0px`. If the project has `motion` or `framer-motion` in `package.json`, match that package's import path (or the established nearby imports when both exist) and use `transition: { type: "spring", duration: 0.3, bounce: 0 }` — bounce must always be `0`. If no motion library is installed, keep both icons in the DOM (one absolute-positioned) and cross-fade with CSS transitions using `cubic-bezier(0.2, 0, 0, 1)` — this gives both enter and exit animations without any dependency.

### 8. Font Smoothing

Apply `-webkit-font-smoothing: antialiased` to the root layout on macOS for crisper text.

### 9. Tabular Numbers

Use `font-variant-numeric: tabular-nums` for any dynamically updating numbers to prevent layout shift.

### 10. Text Wrapping

Use `text-wrap: balance` on headings. Use `text-wrap: pretty` for body text to avoid orphans.

### 11. Image Outlines

Add a subtle `1px` outline with low opacity to images for consistent depth. The color must be pure black in light mode (`oklch(0 0 0 / 0.1)`) and pure white in dark mode (`oklch(1 0 0 / 0.1)`), never a near-black like slate, zinc, or any tinted neutral. A tinted outline picks up the surface color underneath it and reads as dirt on the image edge.

### 12. Scale on Press

A subtle `scale(0.96)` on click gives buttons tactile feedback. Always use `0.96`. Never use a value smaller than `0.95` — anything below feels exaggerated. Add a `static` prop to disable it when motion would be distracting.

### 13. Skip Animation on Page Load

Use `initial={false}` on `AnimatePresence` to prevent enter animations on first render. Verify it doesn't break intentional entrance animations.

### 14. Never Use `transition: all`

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

### 15. Use `will-change` Sparingly

Only for `transform`, `opacity`, `filter` — properties the GPU can composite. Never use `will-change: all`. Only add when you notice first-frame stutter.

### 16. Minimum Hit Area

Interactive elements should prefer a 44×44px hit area for touch or mobile contexts. In dense desktop interfaces, use at least 40×40px. Extend with a pseudo-element if the visible element is smaller. Never let hit areas of two elements overlap.

### 17. 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; never mix libraries on one surface.

### 18. One SVG, Recolored per State

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

### 19. Motion Restraint

No custom animation on high-frequency interactions: the attention cost repeats on every trigger. Motion is never the only feedback channel; every animated state change also needs a static cue such as color, icon, or label.

## Common Mistakes

| Mistake | Fix |
| --- | --- |
| Same border radius on parent and child | Calculate `outerRadius = innerRadius + padding` |
| Icons look off-center | Adjust optically with padding or fix SVG directly |
| Border used only to fake elevation | Use layered `box-shadow` with transparency; keep structural and state borders |
| Jarring staged entrance or contextual exit | Stagger infrequent entrances and keep context-preserving exits subtle |
| Numbers cause layout shift | Apply `tabular-nums` |
| Heavy text on macOS | Apply `antialiased` to root |
| Animation plays on page load | Add `initial={false}` to `AnimatePresence` |
| `transition: all` on elements | Specify exact properties |
| First-frame animation stutter | Add `will-change: transform` (sparingly) |
| Tiny hit areas on small controls | Extend with a pseudo-element to 44×44px for touch/mobile, or at least 40×40px in dense desktop UI |
| Hairline icon beside bold text | Match the stroke width to the text weight |
| Separate icon assets per state | One `currentColor` SVG, states via CSS |
| Filled icons everywhere | Outline as default, fill only for the active state |
| Entrance animation on every hover or keystroke | Instant feedback or ≤150ms opacity/color transition |

## Review Output Format

Use `full` when no review mode is supplied.

| Mode | Coverage | Finding cap |
| --- | --- | --- |
| `quick` | Primary user path and highest-traffic states; report only `HIGH` and `MEDIUM` issues | 5 |
| `full` | Entire requested scope across typography, surfaces, animations, icons, and performance | 15 |

### Scope and Coverage

State the mode, exact scope, framework, styling conventions, and any review boundary. Show what was actually inspected:

| Category | Evidence inspected | Result |
| --- | --- | --- |
| Typography | Files, components, states, or checks | Findings count, `Clear`, or `Not reviewed` with a reason |

Include all five Quick Reference categories. Never imply an uninspected surface was reviewed.

### Findings

Group findings by principle. Use a markdown table with **Severity**, **Location**, **Before**, **After**, and **Why** columns. Include every change made or proposed, not a subset. Never use separate "Before:" / "After:" lines.

- **Severity**: `HIGH` makes an interaction inaccessible, misleading, unreadable, or repeatedly disruptive; `MEDIUM` creates a noticeable usability or consistency problem; `LOW` is isolated polish and appears only in `full` mode.
- **Location**: cite `path/to/file:line`. If the artifact has no source files, cite the exact screen and component instead.
- **Before / After**: show the current implementation and an actionable replacement.
- **Why**: name the violated principle and explain its user impact.

Consolidate a repeated systemic issue into one row and list every affected location. Omit principles with no findings and never pad the report to reach the cap.

### Example

#### Concentric border radius
| Severity | Location | Before | After | Why |
| --- | --- | --- | --- | --- |
| LOW | `src/Card.tsx:28` | `rounded-xl` on card + `rounded-xl` on inner button (`p-2`) | `rounded-2xl` on card (`8 + 8 = 16`), `rounded-lg` on inner button | Nested corners should be concentric |
| LOW | `src/card.css:11` | `border-radius: 16px` on both nested surfaces | Outer `24px`, inner `16px` with `8px` padding | Equal nested radii make the inner surface look pinched |

#### Tabular numbers
| Severity | Location | Before | After | Why |
| --- | --- | --- | --- | --- |
| MEDIUM | `src/Counter.tsx:17` | `<span>{count}</span>` | `<span className="tabular-nums">{count}</span>` | Proportional digits cause changing values to shift |
| LOW | `src/timer.css:8` | Default numerals on a timer | Add `font-variant-numeric: tabular-nums` to the timer | Equal-width digits keep the timer stable |

#### Scale on press
| Severity | Location | Before | After | Why |
| --- | --- | --- | --- | --- |
| LOW | `src/Button.tsx:19` | `<button className="...">` | Add `active:scale-[0.96] transition-transform` | Press feedback makes the control feel responsive |
| MEDIUM | `src/button.css:24` | `scale(0.9)` on press | Raise to `scale(0.96)` | Anything below `0.95` feels exaggerated |

### Considered but Rejected

Include 1–3 real candidates in `quick` mode and 2–5 in `full` mode:

| Location | Candidate | Rejected because |
| --- | --- | --- |
| `src/Card.tsx:28` | Increase the shadow | Existing depth matches the shared surface token; changing one card would reduce consistency |

Do not invent filler. If the scope contains fewer borderline candidates, include the ones that exist and say so.

### Verification and Verdict

After the findings:

1. **Verification**: list the exact commands or interactions run and their observed results. Walk every relevant state and inspect motion at 10% speed when animation is involved. If a check was not run, label it **Not verified** and state what remains.
2. **Verdict**: `Block` if any `HIGH` finding remains, `Needs changes` if only `MEDIUM` or `LOW` findings remain, and `Approve` only when no actionable findings remain. List every unverified check beside the verdict.

When there are no findings, omit the findings table, state "No actionable interface-polish findings", report verification and rejected candidates, and end with `Approve`.