Frontend Design Svelte Skill

Purpose

This skill guides the creation of distinctive, production-grade Svelte frontends that combine Svelte's reactive elegance with exceptional design quality. It integrates all design frameworks: intentional thinking, typography, color, motion, spatial composition, and anti-pattern awareness.

When to Use

• Building production Svelte/SvelteKit frontends
• Creating component libraries with design personality
• Designing interactions that leverage Svelte's reactivity
• Building accessible, mobile-first web applications
• Prototyping high-fidelity designs in code

Core Principles

1. Design Thinking Foundation (Pre-Coding)

Before writing any code, establish intentional design direction:

The Four Critical Questions:

1. Purpose: What problem are we solving? Who are we solving it for?
2. Tone: What emotional response do we want? What aesthetic direction reflects this?
3. Constraints: What are the real technical, temporal, or business limits?
4. Differentiation: What one unforgettable element makes this distinctly ours?

2. Anti-Generic AI Design Standards

Deliberately reject these patterns:

Typography:

• ❌ Avoid: Inter, Roboto, Open Sans as primary choices
• ✅ Prefer: Playfair Display, Crimson Pro, Space Grotesk, IBM Plex, Bricolage Grotesque
• ✅ Use high-contrast pairings: Display + Mono, Serif + Geometric Sans
• ✅ Use size jumps of 3x+, not incremental 1.5x scaling

Color & Theme:

• ❌ Avoid: Material Design trinity (blue, red, green)
• ❌ Avoid: Default SaaS blue (#0099ff) everywhere
• ✅ Prefer: Intentional palettes with one unexpected accent
• ✅ Prefer: Warm or cool personality, never neutral grays

Layout & Space:

• ❌ Avoid: Centered, symmetrical "cookie-cutter" layouts
• ✅ Prefer: Asymmetrical compositions with intentional whitespace
• ✅ Use consistent spacing scale: 8px, 12px, 16px, 24px, 32px, 48px, 64px

Motion:

• ❌ Avoid: Linear timing, instantaneous interactions
• ✅ Prefer: Orchestrated animations with easing functions
• ✅ Prefer: Staggered reveals, delightful hover surprises

Svelte-Specific Guidance

TypeScript Setup

Always use TypeScript in Svelte components:

<script lang="ts">
  import type { ComponentProps } from 'svelte'

  interface Props {
    title: string
    count: number
    onAction?: () => void
  }

  let { title, count, onAction }: Props = $props()
</script>

Reactivity with $:

Leverage Svelte's reactive declarations for dynamic styling and state:

<script lang="ts">
  let theme: 'light' | 'dark' = $state('light')
  let isHovered = $state(false)

  // Reactive computed values
  let backgroundColor = $derived(
    theme === 'light' ? 'var(--color-bg-light)' : 'var(--color-bg-dark)'
  )

  let shadowIntensity = $derived(isHovered ? '0.2' : '0.1')
</script>

Scoped Styles with CSS Variables

Svelte's scoped styles are default. Use CSS custom properties for theming:

<style>
  :global(:root) {
    --color-primary: #8b4513;
    --color-accent: #d4a574;
    --color-bg: #faf8f3;
    --font-display: 'Playfair Display', serif;
    --font-body: 'IBM Plex Sans', sans-serif;
    --spacing-unit: 8px;
  }

  .card {
    background: var(--color-bg);
    padding: calc(var(--spacing-unit) * 3);
    border-radius: 8px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, var(--shadow-intensity));
    transition: all 0.3s cubic-bezier(0.34, 1.56, 0.64, 1);
  }

  .card:hover {
    --shadow-intensity: 0.15;
    transform: translateY(-4px);
  }
</style>

Svelte Transitions & Animations

Use Svelte's built-in transitions for elegant animations:

<script lang="ts">
  import { fade, fly, scale, slide } from 'svelte/transition'
  import { cubicOut, elasticOut } from 'svelte/easing'

  let isVisible = $state(true)
  let showDetails = $state(false)
</script>

<!-- Fade in on mount -->
<div in:fade={{ duration: 300 }} out:fade={{ duration: 200 }}>
  Content
</div>

<!-- Orchestrated entrance with stagger -->
<div
  in:fly={{ y: 50, duration: 600, delay: 100, easing: cubicOut }}
  out:fly={{ y: 20, duration: 300 }}
>
  Hero section
</div>

<!-- Elastic expand on interaction -->
{#if showDetails}
  <div
    in:scale={{ start: 0.95, duration: 400, easing: elasticOut }}
    out:scale={{ duration: 200 }}
  >
    Detailed content
  </div>
{/if}

<!-- Slide for list items (staggered) -->
<ul>
  {#each items as item (item.id)}
    <li
      in:slide={{ duration: 400, delay: index * 50 }}
      out:slide={{ duration: 200 }}
    >
      {item.name}
    </li>
  {/each}
</ul>

Stores for Global State & Theme Management

Use Svelte stores for theme, animations, and global UI state:

<!-- lib/stores/theme.ts -->
import { writable, derived } from 'svelte/store'

export const isDarkMode = writable(false)

export const themeVariables = derived(isDarkMode, ($isDarkMode) => ({
  bgColor: $isDarkMode ? '#1a1a1a' : '#faf8f3',
  textColor: $isDarkMode ? '#f5f5f5' : '#333333',
  accentColor: '#d4a574',
  shadows: $isDarkMode ? 'rgba(0,0,0,0.4)' : 'rgba(0,0,0,0.1)',
}))

<!-- Usage in component -->
<script lang="ts">
  import { isDarkMode, themeVariables } from '$lib/stores/theme'
</script>

<div style:background-color={$themeVariables.bgColor}>
  Content
</div>

Accessibility & Semantic HTML

Svelte's approach to accessibility:

<script lang="ts">
  let isMenuOpen = $state(false)
  let focusedIndex = $state(-1)
</script>

<!-- Semantic structure -->
<nav aria-label="Main navigation">
  <button
    aria-expanded={isMenuOpen}
    aria-controls="main-menu"
    aria-label="Toggle navigation menu"
  >
    Menu
  </button>

  <ul id="main-menu" role="menubar" hidden={!isMenuOpen}>
    {#each menuItems as item (item.id)}
      <li role="none">
        <a href={item.href} role="menuitem">
          {item.label}
        </a>
      </li>
    {/each}
  </ul>
</nav>

<!-- Form accessibility -->
<form>
  <label for="email">Email address</label>
  <input
    id="email"
    type="email"
    required
    aria-required="true"
    aria-describedby="email-hint"
  />
  <small id="email-hint">We'll never share your email.</small>
</form>

Mobile-First Responsive Design

Use Svelte's class directives and media queries:

<script lang="ts">
  let viewport: 'mobile' | 'tablet' | 'desktop' = $state('mobile')
  let windowWidth = $state(0)

  $effect(() => {
    if (windowWidth < 640) viewport = 'mobile'
    else if (windowWidth < 1024) viewport = 'tablet'
    else viewport = 'desktop'
  })
</script>

<svelte:window bind:innerWidth={windowWidth} />

<div class="container" class:is-mobile={viewport === 'mobile'}>
  <header class:is-compact={viewport === 'mobile'}>
    <!-- Mobile-optimized header -->
  </header>
</div>

<style>
  .container {
    padding: calc(var(--spacing-unit) * 4);
  }

  .container.is-mobile {
    padding: calc(var(--spacing-unit) * 2);
  }

  header.is-compact {
    font-size: 18px;
  }

  @media (min-width: 640px) {
    header {
      font-size: 24px;
    }
  }
</style>

8-Phase Development Workflow

Phase 1: Design Thinking & Intent Definition

Input: Feature requirements, target users, problem statement

Actions:

• Answer the 4 Critical Questions (Purpose, Tone, Constraints, Differentiation)
• Define emotional intent (trustworthy, energetic, sophisticated, direct, warm, bold)
• Document design constraints (technical, temporal, business, creative)
• Identify the unforgettable element that makes this distinctly yours

Deliverable: Design brief with clear direction

Phase 2: Design System & Token Definition

Input: Design brief and tone direction

Actions:

• Define typography: Display font, Body font, Monospace font
• Create color palette: Base colors, accents, semantic colors (success, error, warning)
• Establish spacing scale: 8px increments (8, 12, 16, 24, 32, 48, 64)
• Define motion easing curves and durations
• Plan component system structure

Deliverable: Design tokens in CSS variables and Svelte stores

<!-- $lib/styles/tokens.css -->
:root {
  /* Typography */
  --font-display: 'Playfair Display', serif;
  --font-body: 'IBM Plex Sans', sans-serif;
  --font-mono: 'JetBrains Mono', monospace;

  --size-display: 88px;
  --size-h1: 48px;
  --size-h2: 28px;
  --size-body: 16px;
  --size-small: 12px;

  /* Colors */
  --color-bg: #faf8f3;
  --color-text: #2a2a2a;
  --color-accent: #d4a574;
  --color-accent-dark: #8b4513;

  /* Motion */
  --easing-out: cubic-bezier(0.16, 0.04, 0.04, 1);
  --easing-elastic: cubic-bezier(0.34, 1.56, 0.64, 1);
  --duration-quick: 200ms;
  --duration-standard: 400ms;
  --duration-slow: 600ms;
}

Phase 3: Component Architecture & TypeScript Contracts

Input: Design tokens and feature requirements

Actions:

• Define component props with TypeScript interfaces
• Create component hierarchy (atoms → molecules → organisms)
• Plan state management strategy
• Define event handling patterns
• Document component accessibility requirements

Deliverable: Typed component structure

<!-- lib/components/Button.svelte -->
<script lang="ts">
  import { cubicOut } from 'svelte/easing'

  interface Props {
    variant?: 'primary' | 'secondary' | 'outline'
    size?: 'small' | 'medium' | 'large'
    disabled?: boolean
    ariaLabel?: string
    onclick?: () => void
  }

  let {
    variant = 'primary',
    size = 'medium',
    disabled = false,
    ariaLabel,
    onclick,
  }: Props = $props()
</script>

<button
  class="button {variant} {size}"
  {disabled}
  aria-label={ariaLabel}
  on:click={onclick}
  in:scale={{ start: 0.95, duration: 200, easing: cubicOut }}
>
  <slot />
</button>

Phase 4: Interaction & Motion Design

Input: Component structure and design tokens

Actions:

• Map Svelte transitions to design intent
• Plan orchestrated page load sequences (staggered reveals)
• Define hover/focus states with motion
• Plan scroll trigger animations
• Create state-based animations for interactions

Deliverable: Transition patterns and animation sequences

Phase 5: Responsive Design & Layout System

Input: Component library and motion patterns

Actions:

• Build mobile-first CSS grid/flex layout system
• Define breakpoints and responsive behaviors
• Create viewport-aware components
• Test touch interactions on mobile
• Ensure all animations perform well on mobile devices

Deliverable: Responsive component library

Phase 6: Theming & Color Implementation

Input: Design tokens and component library

Actions:

• Implement CSS variable theming system
• Create light/dark mode support (if needed)
• Apply color palette to components
• Ensure sufficient color contrast (WCAG AA minimum)
• Create dynamic theme switcher

Deliverable: Fully themed component system

Phase 7: Accessibility & ARIA Implementation

Input: All components and interactions

Actions:

• Add semantic HTML structure
• Implement ARIA labels and roles
• Test keyboard navigation
• Ensure focus states are visible
• Validate against WCAG 2.1 AA standards
• Test with screen readers

Deliverable: Fully accessible component library

Phase 8: Polish & Performance

Input: Complete feature implementation

Actions:

• Optimize animation performance (use will-change, GPU acceleration)
• Add micro-interactions and easter eggs
• Test on real devices and browsers
• Measure Core Web Vitals
• Refine motion based on performance data
• Final design review against intent

Deliverable: Production-ready application

Anti-Generic-AI Checklist

Use these checks before finalizing any design or component:

Typography:

• YES to high-contrast font pairings (Display + Mono, Serif + Sans)
• YES to size jumps of 3x+ (88px, 48px, 28px, 16px)
• YES to weight extremes (300/700 vs 400/600)
• NO to Inter, Roboto, Open Sans as primary choice

Color & Theme:

• YES to intentional palette with personality
• YES to one unexpected accent color
• YES to warm or cool personality (not neutral)
• NO to Material Design trinity or default SaaS blue

Layout & Space:

• YES to asymmetrical compositions
• YES to generous whitespace with intent
• YES to consistent spacing scale (8px increments)
• NO to centered, symmetrical "cookie-cutter" layouts

Motion & Animation:

• YES to Svelte transitions for smooth animations
• YES to orchestrated/staggered reveals
• YES to easing functions (elastic, cubic-bezier)
• YES to reactive declarations for dynamic styling
• YES to scoped styles with CSS variables
• NO to linear timing or instant interactions
• NO to animation-heavy design that distracts

Svelte-Specific:

• YES to TypeScript in <script lang="ts">
• YES to reactive declarations with $:
• YES to scoped styles with CSS variables
• YES to Svelte transitions for elegant motion
• YES to stores for global state and theme
• YES to semantic HTML and ARIA attributes

Example Component Patterns

Animated Card with Hover Delight

<script lang="ts">
  import { fly, scale } from 'svelte/transition'
  import { cubicOut, elasticOut } from 'svelte/easing'

  let isHovered = $state(false)

  interface Props {
    title: string
    description: string
    image?: string
  }

  let { title, description, image }: Props = $props()
</script>

<article
  in:fly={{ y: 40, duration: 500, easing: cubicOut }}
  class="card"
  on:mouseenter={() => (isHovered = true)}
  on:mouseleave={() => (isHovered = false)}
>
  {#if image}
    <img src={image} alt="" class="card-image" />
  {/if}

  <div class="card-content">
    <h3>{title}</h3>
    <p>{description}</p>

    {#if isHovered}
      <button
        in:scale={{ start: 0.8, duration: 300, easing: elasticOut }}
        class="card-action"
      >
        Learn More
      </button>
    {/if}
  </div>
</article>

<style>
  .card {
    background: var(--color-bg);
    border-radius: 12px;
    overflow: hidden;
    transition: all 0.4s cubic-bezier(0.34, 1.56, 0.64, 1);
    cursor: pointer;
  }

  .card:hover {
    transform: translateY(-12px);
    box-shadow: 0 24px 48px rgba(0, 0, 0, 0.15);
  }

  .card-image {
    width: 100%;
    height: 240px;
    object-fit: cover;
  }

  .card-content {
    padding: calc(var(--spacing-unit) * 3);
  }

  h3 {
    font-family: var(--font-display);
    font-size: var(--size-h2);
    font-weight: 700;
    margin: 0 0 calc(var(--spacing-unit) * 2) 0;
    color: var(--color-text);
  }

  p {
    font-family: var(--font-body);
    font-size: var(--size-body);
    line-height: 1.6;
    color: rgba(0, 0, 0, 0.7);
    margin: 0;
  }

  .card-action {
    margin-top: calc(var(--spacing-unit) * 2);
    padding: calc(var(--spacing-unit) * 1.5) calc(var(--spacing-unit) * 3);
    background: var(--color-accent);
    color: white;
    border: none;
    border-radius: 6px;
    font-family: var(--font-body);
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease-out;
  }

  .card-action:hover {
    background: var(--color-accent-dark);
    transform: scale(1.05);
  }
</style>

Staggered List Animation

<script lang="ts">
  import { slide } from 'svelte/transition'
  import { cubicOut } from 'svelte/easing'

  interface ListItem {
    id: string
    label: string
  }

  interface Props {
    items: ListItem[]
  }

  let { items }: Props = $props()
</script>

<ul class="list">
  {#each items as item, index (item.id)}
    <li
      in:slide={{
        duration: 400,
        delay: index * 50,
        easing: cubicOut,
      }}
      out:slide={{ duration: 200 }}
    >
      <span class="list-number">{index + 1}</span>
      <span class="list-label">{item.label}</span>
    </li>
  {/each}
</ul>

<style>
  .list {
    list-style: none;
    padding: 0;
    margin: 0;
  }

  li {
    display: flex;
    align-items: center;
    padding: calc(var(--spacing-unit) * 2) calc(var(--spacing-unit) * 3);
    border-bottom: 1px solid rgba(0, 0, 0, 0.1);
    transition: background-color 0.3s ease-out;
  }

  li:hover {
    background-color: rgba(0, 0, 0, 0.02);
  }

  .list-number {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 32px;
    height: 32px;
    margin-right: calc(var(--spacing-unit) * 2);
    background: var(--color-accent);
    color: white;
    border-radius: 50%;
    font-weight: 600;
    font-size: 13px;
  }

  .list-label {
    font-family: var(--font-body);
    font-size: var(--size-body);
    color: var(--color-text);
  }
</style>

Svelte-Specific Best Practices

1. Type Safety: Always use TypeScript in component scripts
2. Reactivity: Leverage $derived for computed values and $effect for side effects
3. Transitions: Use built-in svelte/transition for all animations
4. Scoped Styles: Rely on Svelte's default scoped styling; use :global() sparingly
5. CSS Variables: Store design tokens as CSS variables for dynamic theming
6. Stores: Use writable for theme, animation state, and global UI state
7. Accessibility: Always include semantic HTML, ARIA labels, and proper focus management
8. Performance: Use bind: carefully, memoize expensive computations with $derived

Resources & References

• Svelte Documentation: https://svelte.dev
• SvelteKit: https://kit.svelte.dev
• Design System Prompts: See design-thinking.md, aesthetics-base.md, motion.md, typography.md, anti-patterns.md
• WCAG 2.1 Accessibility: https://www.w3.org/WAI/WCAG21/quickref/

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Ready to build distinctive, intentional Svelte frontends? Start with Phase 1: Design Thinking & Intent Definition. Never skip the pre-coding work.