Ui Design

UI Design

> Professional web interfaces through systematic layouts, clear visual hierarchy, and consistent components.

Scope

Use this skill when: You are creating layouts, designing UI components, establishing visual hierarchy, defining grid systems, building styleguides or design tokens, or auditing existing interfaces for visual consistency.

Principles

1. User-Centered Design Over Aesthetics

Every design decision is guided by the needs of the target audience. An interface that is visually impressive but poorly usable has failed.

2. Visual Hierarchy Determines Perception

Size, color, contrast, and position control what users see first. Every page needs exactly ONE primary focal point.

3. Consistency Builds Trust

Identical elements must look and behave identically everywhere. Inconsistency increases cognitive load.

4. Reduction Is Strength

Every element without a measurable purpose must be removed. Whitespace is not wasted space -- it improves readability and focus.

5. The Grid Is the Foundation

Without a grid system, there is no professional layout. The grid enforces alignment, creates rhythm, and enables responsive design.

Rules

Layout & Grid

• DO: Use a 12-column grid as the basis for desktop (divisible by 2, 3, 4, 6).
• DO: Use an 8px baseline grid for all spacing (8, 16, 24, 32, 48, 64px).
• DO: Set a maximum content width of 1200-1440px.
• DON'T: Mix different grid systems within one application.
• DON'T: Place more than 3-4 content blocks side by side on desktop, or more than 1-2 on mobile.

Visual Hierarchy

• DO: Establish at least 3 hierarchy levels: primary (hero), secondary (features), tertiary (details).
• DO: Make the most important element at least 1.5x larger than the second most important.
• DON'T: Use more than 3 different font sizes within a single viewport area.
• DON'T: Place multiple equally weighted CTAs in the same viewport. One primary CTA per viewport.

Components

• DO: Use established UI patterns for standard interactions.
• DO: Define clear states for all input elements: default, hover, focus, active, disabled, error.
• DO: Include progress indicators for multi-step processes.
• DON'T: Invent new interaction patterns for standard tasks.

Whitespace & Spacing

• DO: Use generous whitespace between sections (min. 64-96px vertical on desktop).
• DO: Place related elements close together, separate groups far apart (Gestalt law of proximity).
• DON'T: Fill empty space with decorative elements.

Styleguide & Design Tokens

• DO: Create a UI styleguide BEFORE implementation: colors, typography, icons, buttons, spacing.
• DO: Use design tokens: --color-primary, --spacing-lg, --font-heading.
• DON'T: Use magic numbers (hard-coded pixel values) instead of token references.

Patterns

Detailed pattern descriptions: see references/patterns.md

Hero Section

Large-scale visual + concise headline (max. 7 words) + subline + primary CTA in a contrasting color. Must communicate the core message within 3 seconds.

Card Layout (Bento Grid)

Modular cards in a grid. Each card is a self-contained information unit. Max. 6-9 cards in the initial viewport on desktop, 2-3 on mobile.

Split Screen

Two equally weighted halves -- one visual, one textual. Stack vertically on mobile.

Sticky Navigation

Header remains visible on scroll. Active section is highlighted. Max. height 64px.

Modals & Overlays

Centered overlay with a dimmed background. Clear close button. Focus trap. Escape closes.

Anti-Patterns

Overloaded Interfaces

Too many elements, too little whitespace, competing CTAs. Solution: One page = one primary goal.

Inconsistent Styles

Buttons that look different across pages. Solution: Create and enforce a styleguide.

Dark Patterns

Manipulative design (hidden unsubscribe buttons, confirm shaming). Solution: Every interaction must be transparent and in the user's interest.

Carousel as Content Strategy

Auto-carousels: only slide 1 is noticed (< 1% click rate on slides 2+). Solution: Static hero or manual tabs.

Scroll Hijacking

Overriding native scroll behavior. Solution: Preserve native scrolling, keep animations subtle.

Checklist

• [ ] 12-column grid with 8px baseline defined?
• [ ] Maximum content width set (1200-1440px)?
• [ ] Visual hierarchy verifiable: primary, secondary, tertiary levels?
• [ ] Only ONE primary CTA per viewport?
• [ ] All components have defined states (default, hover, focus, active, disabled, error)?
• [ ] Whitespace between sections consistent and generous (min. 64px)?
• [ ] Styleguide/design tokens in place and applied?
• [ ] No magic numbers -- all values reference tokens?
• [ ] No scroll hijacking or auto-carousel?
• [ ] Dark patterns ruled out?
• [ ] Modals have focus trap and escape-to-close?

Cross-References

• web-typography -- Font selection and sizing for hierarchy
• color-theory -- Color systems and contrast rules
• accessibility -- WCAG compliance for all UI components
• usability -- Heuristics for user-friendliness
• responsive-design -- Grid behavior across breakpoints
• design-trends -- Current award-winning UI patterns
• component-patterns -- Technical component implementation
• visual-direction -- Visual direction and style decisions

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: flitzrrr
• Source: flitzrrr/frontend-design-skills
• License: MIT

Install and usage instructions live in the source repository linked above.