frontend-design

name	frontend-design
description	Production-grade UI for web and mobile — design systems, visual hierarchy, distinctive aesthetics. Use for frontend implementation and design decisions.
when_to_use	TRIGGER when: UI, pages, components, or design. DO NOT TRIGGER when: backend or non-visual.

Frontend Design

Production-grade UI design skill combining design system thinking with bold aesthetic execution. Covers web (HTML/CSS/JS, React, Vue, etc.) and mobile (Flutter, React Native, SwiftUI, etc.).

---

MODE DETECTION (FIRST STEP)

Analyze the user's request to determine platform:

Request Pattern	Mode	Focus
HTML, CSS, JS, React, Vue, Next.js, landing page, dashboard, web app	WEB	Browser viewport, responsive breakpoints, CSS animations
Flutter, React Native, SwiftUI, Kotlin, mobile app, iOS, Android	MOBILE	Touch targets, safe areas, platform depth, native patterns
Unspecified	WEB	Default to web unless context suggests mobile

---

DESIGN PROCESS (BEFORE CODING)

Before writing any code, commit to a BOLD aesthetic direction by answering four questions:

1. Purpose: What problem does this interface solve? Who uses it?
2. Tone: Pick a clear direction — brutally minimal, maximalist chaos, retro-futuristic, organic/natural, luxury/refined, playful/toy-like, editorial/magazine, brutalist/raw, art deco/geometric, soft/pastel, industrial/utilitarian. Commit fully.
3. Constraints: Technical requirements (framework, performance, accessibility)
4. Differentiation: What is the ONE thing someone will remember about this interface?

CRITICAL: Choose a clear conceptual direction and execute with precision. Bold maximalism and refined minimalism both work — the key is intentionality, not intensity.

Then implement working code that is:

• Production-grade and functional
• Visually striking and memorable
• Cohesive with a clear aesthetic point-of-view
• Meticulously refined in every detail

Design-First Workflow

1. Design the actual piece of functionality first — not the shell, navigation, or chrome
2. Work in grayscale first — add color after hierarchy is clear
3. Establish systems (spacing, type, color) before detailed design
4. Details come later — work in cycles

---

DESIGN SYSTEMS

Spacing Scale

Constrain to a fixed set. Values should never be closer than ~25% apart.

Web (px):

Token	Size	Use Case
1	4	Micro gaps
2	8	Tight, within components
3	12	Related elements
4	16	Section padding
6	24	Between sections
8	32	Major separation
12	48	Large gaps
16	64	Hero spacing
24	96	Maximum separation

Mobile (dp/pt):

Token	Size	Use Case
xs	4	Micro gaps, icon padding
sm	8	Within components
md	12	Related elements
base	16	Standard screen padding
lg	24	Between sections
xl	32	Major separation
2xl	48	Tablets, hero areas

Type Scale

Web (px):

Size	Role
12	Labels, meta, fine print
14	Body text, default
16	Emphasis, large body
18	Subheadings
20-24	Card/section titles
30-36	Page headings
48-72	Hero/display text

Mobile (sp/pt):

Size	Role
11-12	Captions, labels
14	Body text, default
16	Emphasized body
18-20	Subheadings
24	Screen titles
28-34	Large titles (iOS style)

Shadow Scale

Level	Use Case	Web CSS	Mobile Elevation
1	Buttons, subtle lift	0 1px 2px rgba(0,0,0,0.05)	1-2dp
2	Cards, inputs	0 2px 4px rgba(0,0,0,0.1)	4dp
3	Dropdowns, popovers	0 4px 8px rgba(0,0,0,0.1)	8dp
4	Sticky headers, drawers	0 8px 16px rgba(0,0,0,0.1)	16dp
5	Modals, dialogs	0 16px 32px rgba(0,0,0,0.15)	24dp

Premium shadows: Combine two shadows — a large soft one (direct light) and a tight dark one (ambient occlusion).

box-shadow:
  0 10px 25px rgba(0, 0, 0, 0.15),  /* direct light */
  0 2px 4px rgba(0, 0, 0, 0.12);     /* ambient */

---

VISUAL HIERARCHY

Every element sits at one of three levels:

• Primary: Dark color, bold weight — headlines, key actions (one per section)
• Secondary: Grey — supporting text, dates, descriptions
• Tertiary: Light grey — metadata, copyright, timestamps

Key Principles

• Size isn't everything — use weight and color before increasing size
• Emphasize by de-emphasizing: Make competing elements softer instead of making the target louder
• Labels are a last resort — combine with values ("12 left in stock" > "Stock: 12")
• Semantics are secondary to hierarchy (h1 doesn't have to be the biggest element)
• Icons are visually "heavy" — give them softer colors to balance with text

Button Hierarchy

Level	Style	Rule
Primary	Solid, high-contrast background	One per section maximum
Secondary	Outline or low-contrast fill	Clear but not competing
Tertiary	Styled like links	Discoverable but unobtrusive

Destructive actions: Not always big/red/bold. On confirmation dialogs, yes. On regular pages where delete is secondary, use tertiary styling.

---

COLOR SYSTEM

Use HSL

HSL (Hue, Saturation, Lightness) is intuitive for palette creation. Avoid hex for design decisions.

Build Complete Palettes

Category	Shades	Purpose
Greys	8-10	Text, backgrounds, panels, borders
Primary	5-10	Actions, active states, links
Accents	5-10 each	Success, warning, error, feature highlights

Shade Definition Process

1. Pick base (500): Works as button background
2. Pick edges: 100 (tinted background), 900 (text on light bg)
3. Fill gaps: 700, 300 → 800, 600, 400, 200

Saturation & Hue Adjustments

• Increase saturation as lightness moves away from 50% (extremes look washed out otherwise)
• To lighten: Rotate hue toward 60°, 180°, or 300° (perceived bright hues)
• To darken: Rotate hue toward 0°, 120°, or 240° (perceived dark hues)
• Don't rotate more than 20-30° (looks like different color)

Grey Temperature

• Cool greys: Saturate with blue
• Warm greys: Saturate with yellow/orange
• True black looks unnatural — start with really dark grey

Accessibility Requirements

Text Type	Minimum Contrast Ratio
Normal text (<18px)	4.5:1
Large text (18px+ bold or 24px+)	3:1

Never rely on color alone for meaning. Add icons, text, or patterns.

---

TYPOGRAPHY

Font Selection

Choose distinctive, characterful fonts. Pair a bold display font with a refined body font.

Filtering quality fonts: Ignore typefaces with less than 5 weights (10+ styles including italics). This eliminates 85% of poor choices.

NEVER use: Arial, Inter, Roboto, system-ui, Space Grotesk. These produce forgettable, generic output.

Line-Height Rules

• Small text → taller line-height (1.5-2.0)
• Large headlines → shorter line-height (1.0-1.2)
• Wider content → increase line-height (easier to track to next line)

Line Length

Optimal: 45-75 characters per line (20-35em width). Wider = harder to read.

Letter-Spacing

• Tighten for headlines (fonts optimized for body have wider spacing)
• Increase for ALL-CAPS text (improves readability)
• Trust the typeface designer for body text

Alignment

• Default: Left-aligned
• Center: Only for headlines and short blocks (under 2-3 lines)
• Right-align numbers for column comparison
• Baseline-align mixed font sizes on a single line (not center)

---

LAYOUT & SPACING

Start with Too Much White Space

Start with generous spacing, then remove until satisfied. "A little too much" in isolation = "just enough" in context.

Don't Fill the Whole Screen

1400px available doesn't mean use 1400px. If content needs 600px, use 600px.

Grids Are Overrated

12-column grids cause more harm than good:

• Sidebars at 25% get too wide on large screens, too narrow on small
• Use fixed-width sidebar + flexible content area
• Use max-width on components, only shrink when necessary

Avoid Ambiguous Spacing

More space between groups than within groups. Applies to:

• Form labels and inputs
• Section headings in articles
• List items and groups
• Horizontal component layouts

Responsive Sizing

Large elements shrink faster than small elements across breakpoints. Don't use fixed ratios.

---

DEPTH & MOTION

Emulating Light

Light comes from above:

• Raised elements (buttons, cards): Lighter top edge + shadow below
• Inset elements (inputs, wells): Lighter bottom edge + shadow above

Interactive Shadows

• Drag: Increase shadow (element pops above others)
• Press: Decrease shadow (pressed into surface)

Flat Design with Depth

Depth without shadows: lighter than background = raised, darker = inset. Solid shadows (no blur) maintain flat aesthetic.

Platform-Aware Depth (Mobile)

Platform	Approach
iOS	Subtle shadows, blur/frosted glass, less elevation
Android	Material elevation system, layered surfaces

Motion

Focus on high-impact moments:

• One well-orchestrated page load with staggered reveals (animation-delay) > scattered micro-interactions
• Scroll-triggered animations and hover states that surprise
• Prioritize CSS-only solutions for web
• Use Motion library for React when available
• Match complexity to aesthetic: maximalist → elaborate effects, minimalist → subtle precision

---

SPATIAL COMPOSITION

Create unexpected layouts:

• Asymmetry and overlap
• Diagonal flow and grid-breaking elements
• Generous negative space OR controlled density
• Cross-background elements for depth without shadows

---

VISUAL DETAILS

Create atmosphere and depth rather than defaulting to solid colors:

• Gradient meshes, noise textures, geometric patterns
• Layered transparencies, dramatic shadows
• Decorative borders, custom cursors, grain overlays
• Accent borders on cards, nav items, alerts, headlines
• Background variety: subtle gradients (hues within 30°), repeating patterns, geometric shapes

---

MOBILE-SPECIFIC PATTERNS

Touch Targets

Platform	Minimum	Comfortable
iOS	44×44 pt	48×48 pt
Android	48×48 dp	56×56 dp

Add invisible padding if icon is smaller than minimum target.

Safe Areas

Respect device notches and home indicators. Never place interactive elements in unsafe areas.

Navigation Patterns

Pattern	Use Case
Bottom navigation	3-5 primary destinations, icons + labels
Tab bar (top)	Content categories
Navigation drawer	Many destinations
Bottom sheet	Contextual actions

Mobile Forms

• Full-width inputs with horizontal padding
• Label above or floating
• Helper text below, error state with red border + message
• Primary button: Full width at bottom or FAB

Loading States

• Skeleton screens (preferred over spinners)
• Shimmer effect for content placeholders
• Pull to refresh for list content

Empty States

Design empty states as first impressions:

• Illustration or icon to grab attention
• Clear title and helpful description
• Call-to-action button
• Hide irrelevant UI (tabs, filters that don't work yet)

---

FINISHING TOUCHES

Supercharge Defaults

• Bulleted lists → contextual icons (checkmarks, arrows, padlocks)
• Blockquotes → oversized quote marks with accent color
• Links → custom thick/colorful underlines
• Form controls → brand-colored selected states

Fewer Borders

Too many borders = busy design. Alternatives:

• Box shadow: 0 0 0 1px rgba(0,0,0,0.05)
• Different background colors for adjacent sections
• Extra spacing between elements

Working with Images

• Text on images: Semi-transparent overlay, lower contrast, colorize, or text shadow
• Don't scale icons beyond intended size (16-24px) — enclose in shape instead
• User content: Fixed containers + object-fit: cover + subtle inner shadow

---

ANTI-PATTERNS

Anti-Pattern	Fix
Generic fonts (Inter, Roboto, Arial, system-ui)	Choose distinctive, characterful typefaces
Purple gradients on white backgrounds	Commit to a cohesive, context-specific palette
Predictable layouts and component patterns	Use asymmetry, overlap, unexpected composition
Grey text on colored backgrounds	Hand-pick colors based on background hue
Filling the whole screen when content needs less	Use max-width, let content breathe
Ambiguous spacing between groups	More space between groups than within
Relative sizing across breakpoints	Large elements shrink faster than small ones
Touch targets under 44pt/48dp	Add invisible padding to meet minimums
Ignoring safe areas (notch, home indicator)	Respect platform safe area insets
Color as sole communication channel	Add icons, text, or patterns alongside color
Cookie-cutter design across generations	Every design must be unique and context-specific
Converging on common font/color choices	Vary themes, fonts, and aesthetics deliberately

---

Output Guidance

When generating frontend code, structure output as: