heartbeat-design-system

name: heartbeat-design-system description: Apply the Heartbeat design system when building or styling UI: 8pt spacing, limited palette (white, #191919, CTA #FF8C5F), natural easing, structured layouts. Use when the user or project references Heartbeat, this design system, or when implementing interfaces that should follow simplicity, lightness, and ease.

Heartbeat Design System

Apply this skill when creating or updating UI that must follow the Heartbeat design system. Core principle: design is based on simplicity—lightness, freedom, ease. Use limited styles, intentional spacing, minimal color, and motion with natural easing.

When to Use

• User or project specifies Heartbeat design system
• Building components, pages, or layouts that should feel light and minimal
• Styling CSS/SCSS, Tailwind, or design tokens for this system

Spacing (8pt grid)

Base unit: 8px. Use multiples only: 8, 16, 24, 32, 40, 48, 56, 64, ... (8×n).
Exception: 4px only when strictly necessary.

• Unrelated elements: large separation
• Larger components: larger surrounding space
• White space is structural, not decorative

Examples:

padding: 16px;
margin-bottom: 32px;
gap: 24px;

In Tailwind, prefer: p-4 (16px), gap-6 (24px), mb-8 (32px), etc., and avoid arbitrary values that break the grid.

Color

• Keep approximate 80/10/10 balance. CTA only for actions; keep it visually distinct.
• No decorative color; do not introduce new colors.

CSS variables example:

--heartbeat-bg: #FFFFFF;
--heartbeat-text: #191919;
--heartbeat-cta: #FF8C5F;

Typography

• Line length: 40–60 characters per line
• Use the project’s predefined font scale; no arbitrary font sizes
• Paragraph spacing: minimum 16px; prefer 24px or 32px

Motion

Default easing: cubic-bezier(0.77, 0, 0.175, 1)
No linear animations. Motion should feel organic: subtle anticipation, smooth deceleration.

transition: all 1s cubic-bezier(0.77, 0, 0.175, 1);

Layout

• Unlimited elements allowed; limited styles enforced
• Structured asymmetry is allowed; spacing can look varied but must follow 8pt logic
• Prioritize breathing space over density; avoid clutter and excessive alignment changes

Illustration (when applicable)

• Background: #191919
• Small elements: #FFFFFF with 2px #191919 border
• Text on dark: only on light surfaces. Consistent stroke thickness; no extra color styles.
• Style: “controlled chaos”—precise details, no additional colors.

Green shape (brand element)

Represents speed, proactivity, adaptability. Use as an active, dynamic element in composition or motion; not purely decorative.

Do / Do not

Do:

• Use 8pt spacing grid
• Use only the defined palette
• Use the defined easing curve
• Follow typography scale
• Keep layouts breathing

Do not:

• Add random font sizes
• Add new colors
• Use linear easing
• Overcrowd layouts
• Break the spacing system

Full spec

For the complete developer spec (case study structure, implementation constraints, emotional direction), see reference.md.