Design engineering for Claude Code. Build interfaces with craft, memory, and enforcement. Maintains consistent design decisions across sessions - make choices once, enforce them automatically.
Build interfaces with intention, consistency, and memory. This skill helps you establish design direction, remember your decisions across sessions, and maintain systematic consistency.
Before building any UI, detect the mode:
Check for .design-engineer/system.md:
package.json or .git? → ESTABLISH MODE (create system)APPLY MODE (system exists):
.design-engineer/system.mdESTABLISH MODE (real project, no system):
tRPC, Prisma, data tables → Dashboard/AdminDetected: [Dashboard] → Suggests [Precision & Density, Cool slate, Borders-only]
Does this direction fit? (y/n/customize)
Created foundations:
- Direction: Precision & Density
- Foundation: Cool (slate)
- Depth: Borders-only
- Patterns: Button (36px h), Card (border, 16px pad)
Save to .design-engineer/system.md? (y/n)
PRINCIPLES ONLY (no system needed):
Before writing any code, commit to a design direction. Don't default. Think about what this specific product needs to feel like.
Enterprise/SaaS UI has more range than you think. Consider these directions:
Precision & Density — Tight spacing, monochrome, information-forward. For power users who live in the tool. Think Linear, Raycast, terminal aesthetics.
Warmth & Approachability — Generous spacing, soft shadows, friendly colors. For products that want to feel human. Think Notion, Coda, collaborative tools.
Sophistication & Trust — Cool tones, layered depth, financial gravitas. For products handling money or sensitive data. Think Stripe, Mercury, enterprise B2B.
Boldness & Clarity — High contrast, dramatic negative space, confident typography. For products that want to feel modern and decisive. Think Vercel, minimal dashboards.
Utility & Function — Muted palette, functional density, clear hierarchy. For products where the work matters more than the chrome. Think GitHub, developer tools.
Data & Analysis — Chart-optimized, technical but accessible, numbers as first-class citizens. For analytics, metrics, business intelligence.
Pick one. Or blend two. But commit to a direction that fits the product.
Don't default to warm neutrals. Consider the product:
Light or dark? Dark modes aren't just light modes inverted. Dark feels technical, focused, premium. Light feels open, approachable, clean. Choose based on context.
Accent color — Pick ONE that means something. Blue for trust. Green for growth. Orange for energy. Violet for creativity. Don't just reach for the same accent every time.
The content should drive the layout:
Typography sets tone. Don't always default:
These apply regardless of design direction. This is the quality floor.
All spacing uses a 4px base grid:
4px - micro spacing (icon gaps)8px - tight spacing (within components)12px - standard spacing (between related elements)16px - comfortable spacing (section padding)24px - generous spacing (between sections)32px - major separationTLBR must match. If top padding is 16px, left/bottom/right must also be 16px. Exception: when content naturally creates visual balance.
/* Good */
padding: 16px;
padding: 12px 16px; /* Only when horizontal needs more room */
/* Bad */
padding: 24px 16px 12px 16px;
Stick to the 4px grid. Sharper corners feel technical, rounder corners feel friendly. Pick a system and commit:
Don't mix systems. Consistency creates coherence.
Match your depth approach to your design direction. Depth is a tool, not a requirement. Different products need different approaches:
Borders-only (flat) — Clean, technical, dense. Works for utility-focused tools where information density matters more than visual lift. Linear, Raycast, and many developer tools use almost no shadows — just subtle borders to define regions. This isn't lazy; it's intentional restraint.
Subtle single shadows — Soft lift without complexity. A simple 0 1px 3px rgba(0,0,0,0.08) can be enough. Works for approachable products that want gentle depth without the weight of layered shadows.
Layered shadows — Rich, premium, dimensional. Multiple shadow layers create realistic depth for products that want to feel substantial. Stripe and Mercury use this approach. Best for cards that need to feel like physical objects.
Surface color shifts — Background tints establish hierarchy without any shadows. A card at #fff on a #f8fafc background already feels elevated. Shadows can reinforce this, but color does the heavy lifting.
Choose ONE approach and commit. Mixing flat borders on some cards with heavy shadows on others creates visual inconsistency.
/* Borders-only approach */
--border: rgba(0, 0, 0, 0.08);
--border-subtle: rgba(0, 0, 0, 0.05);
border: 0.5px solid var(--border);
/* Single shadow approach */
--shadow: 0 1px 3px rgba(0, 0, 0, 0.08);
/* Layered shadow approach (when appropriate) */
--shadow-layered:
0 0 0 0.5px rgba(0, 0, 0, 0.05),
0 1px 2px rgba(0, 0, 0, 0.04),
0 2px 4px rgba(0, 0, 0, 0.03),
0 4px 8px rgba(0, 0, 0, 0.02);
The craft is in the choice, not the complexity. A flat interface with perfect spacing and typography is more polished than a shadow-heavy interface with sloppy details.
Monotonous card layouts are lazy design. 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, another a two-column split.
Design each card's internal structure for its specific content — but keep the surface treatment consistent: same border weight, shadow depth, corner radius, padding scale, typography. Cohesion comes from the container chrome, not from forcing every card into the same layout template.
UI controls deserve container treatment. Date pickers, filters, dropdowns — these should feel like crafted objects sitting on the page, not plain text with click handlers.
Never use native form elements for styled UI. Native <select>, <input type="date">, and similar elements render OS-native dropdowns and pickers that cannot be styled. Build custom components instead:
Custom select triggers must use display: inline-flex with white-space: nowrap to keep text and chevron icons on the same row. Without this, flex children can wrap to new lines.
Numbers, IDs, codes, timestamps belong in monospace. Use tabular-nums for columnar alignment. Mono signals "this is data."
Use Phosphor Icons (@phosphor-icons/react). Icons clarify, not decorate — if removing an icon loses no meaning, remove it.
Give standalone icons presence with subtle background containers.
cubic-bezier(0.25, 1, 0.5, 1)Build a four-level system: foreground (primary) → secondary → muted → faint. Use all four consistently.
Gray builds structure. Color only appears when it communicates: status, action, error, success. Decorative color is noise.
When building data-heavy interfaces, ask whether each use of color is earning its place. Score bars don't need to be color-coded by performance — a single muted color works. Grade badges don't need traffic-light colors — typography can do the hierarchy work. Look at how GitHub renders tables and lists: almost entirely monochrome, with color reserved for status indicators and actionable elements.
Screens need grounding. A data table floating in space feels like a component demo, not a product. Consider including:
When building sidebars, consider using the same background as the main content area. Tools like Supabase, Linear, and Vercel rely on a subtle border for separation rather than different background colors. This reduces visual weight and feels more unified.
Dark interfaces have different needs:
Borders over shadows — Shadows are less visible on dark backgrounds. Lean more on borders for definition. A border at 10-15% white opacity might look nearly invisible but it's doing its job — resist the urge to make it more prominent.
Adjust semantic colors — Status colors (success, warning, error) often need to be slightly desaturated or adjusted for dark backgrounds to avoid feeling harsh.
Same structure, different values — The hierarchy system (foreground → secondary → muted → faint) still applies, just with inverted values.
Run this check before showing work to user:
Spacing check (if system defines grid):
Depth check (if system defines strategy):
Pattern check (if system has patterns):
Color check (if system defines palette):
Fix violations yourself before user sees them. Don't wait for the validation hook to catch them.
Add new patterns when:
Pattern format:
### Button Primary
- Height: 36px
- Padding: 12px 16px
- Radius: 6px
- Font: 14px, 500 weight
- Usage: Header, Dashboard CTA, Forms
Don't document:
Before creating a button, check system.md:
Memory compounds: Each pattern saved makes future work faster and more consistent.
box-shadow: 0 25px 50px...)Every interface should look designed by a team that obsesses over 1-pixel differences. Not stripped — crafted. And designed for its specific context.
Different products want different things. A developer tool wants precision and density. A collaborative product wants warmth and space. A financial product wants trust and sophistication. Let the product context guide the aesthetic.
The goal: intricate minimalism with appropriate personality. Same quality bar, context-driven execution.
