If the current repo has its own rules/skills covering this topic (check .claude/rules/ and repo CLAUDE.md), those take precedence — apply this skill only where they're silent.
Design Principles
Core philosophy: Every interface should look designed by a team that obsesses over 1-pixel differences. Not stripped, crafted. And designed for its specific context.
Avoid AI Sameness
AI-generated UIs have a recognizable "median of the internet" feel. Polished but generic, like everything was designed by the same committee. Break out of that by making deliberate choices instead of reaching for defaults.
AI default patterns to actively avoid:
| AI default | Why it happens | Do this instead |
|---|---|---|
| Indigo/purple gradients | Tailwind's bg-indigo-500 saturated training data | Choose an accent color that fits the product's emotional job |
| Inter or system fonts everywhere | Statistically safest choice | Pick typography that matches the product personality (see Choose Typography below) |
| Three-column icon grid | Every SaaS landing page template uses this | Vary card layouts by content type. Metric cards, feature cards, and testimonial cards should look different from each other |
| Centered hero + CTA button | The default starting point for every landing page | Consider what the user actually needs first. Maybe it's a dense dashboard, a split layout, or content-forward with no hero at all |
| Uniform border-radius on everything | rounded-lg applied without thinking | Pick a radius system and vary it by component role (sharp for data, softer for interactive) |
| White/light gray background + subtle shadow cards | The safest possible surface treatment | Commit to a depth strategy that matches the product (see Depth Strategy below) |
| Decorative gradients on hero sections | Looks "modern" without communicating anything | If using gradients, make them functional (show hierarchy, direct attention) not decorative |
The test: If you swapped your brand name with a competitor's and the design still works, it's too generic. Something about the color foundation, typography, spacing rhythm, or layout density should feel specific to this product.
Controlled imperfection creates character. Perfect symmetry and uniform spacing everywhere reads as machine-generated. Human-designed interfaces have intentional asymmetry: a sidebar slightly narrower than expected, a headline that breaks the grid for emphasis, whitespace that breathes unevenly to create visual rhythm. These are deliberate choices, not sloppiness.
Design Direction (REQUIRED)
Before writing code, commit to a direction. Don't default. Think about what this specific product needs to feel like.
Think About Context
- What does this product do? A finance tool needs different energy than a creative tool.
- Who uses it? Power users want density. Occasional users want guidance.
- What's the emotional job? Trust? Efficiency? Delight? Focus?
- What would make this memorable? Every product has a chance to feel distinctive.
Choose a Personality
| Direction | Feel | When to Use |
|---|---|---|
| Precision & Density | Tight spacing, monochrome, info-forward | Power users who live in the tool. Linear, Raycast, terminal aesthetics. |
| Warmth & Approachability | Generous spacing, soft shadows, friendly | Products that want to feel human. Notion, Coda, collaborative tools. |
| Sophistication & Trust | Cool tones, layered depth, gravitas | Products handling money or sensitive data. Stripe, Mercury. |
| Boldness & Clarity | High contrast, dramatic negative space | Modern, decisive products. Vercel, minimal dashboards. |
| Utility & Function | Muted palette, functional density | Work matters more than chrome. GitHub, developer tools. |
| Data & Analysis | Chart-optimized, technical but accessible | Analytics, metrics, business intelligence. |
Pick one. Or blend two. But commit to a direction that fits the product.
Choose Foundation
Color foundation (don't default to warm):
- Warm (creams, warm grays): approachable, comfortable, human
- Cool (slate, blue-gray): professional, trustworthy, serious
- Pure neutrals (true grays): minimal, bold, technical
- Tinted (slight color cast): distinctive, memorable, branded
Light or dark? Dark feels technical, focused, premium. Light feels open, approachable, clean. Choose based on context.
Accent color: ONE that means something. Blue = trust. Green = growth. Orange = energy. Violet = creativity.
Choose Layout
- Dense grids for information-heavy interfaces where users scan and compare
- Generous spacing for focused tasks where users need to concentrate
- Sidebar nav for multi-section apps with many destinations
- Top nav for simpler tools with fewer sections
Choose Typography
- System fonts: fast, native, invisible (utility-focused products)
- Geometric sans (Geist, Inter): modern, clean, technical
- Humanist sans (SF Pro, Satoshi): warmer, more approachable
- Monospace influence: technical, developer-focused, data-heavy
Card Layouts
Internal layouts should vary by content. A metric card doesn't have to look like a plan card doesn't have to look like a settings card. One might have a sparkline, another an avatar stack, another a progress ring.
Surface treatment stays consistent: same border weight, shadow depth, corner radius, padding scale.
Isolated Controls
Never use native form elements for styled UI. Native <select>, <input type="date"> render OS-native elements that cannot be styled. Build custom components.
Custom select triggers: display: inline-flex with white-space: nowrap to keep text and icons on same row.
Navigation Context
Screens need grounding:
- Navigation (sidebar or top)
- Location indicator (breadcrumbs, active state)
- User context (who's logged in)
When building sidebars, consider using same background as main content. Linear, Vercel use subtle border for separation rather than different backgrounds.
Dark Mode
- Borders over shadows: Shadows less visible on dark backgrounds
- Adjust semantic colors: Desaturate for dark backgrounds
- Same hierarchy, inverted values
Anti-Patterns
Never:
- Dramatic drop shadows (
0 25px 50px...) - Large radius (16px+) on small elements
- Asymmetric padding without reason
- Pure white cards on colored backgrounds
- Thick borders (2px+) for decoration
- Spring/bouncy animations
- Multiple accent colors
- Motion without purpose
The Standard
Different products want different things. A dev tool wants precision and density. A collaborative product wants warmth and space. A financial product wants trust and sophistication.
Same quality bar, context-driven execution.
Implementation
Detect which styling approach the project uses, then load the matching reference:
| Project uses | Load |
|---|---|
| Vanilla CSS, CSS Modules, styled-components, or no Tailwind | references/craft-css.md |
| Tailwind CSS | references/craft-tailwind.md |
If unclear, check for tailwind.config or @tailwind directives in the project. Default to CSS if neither is found.
