github-ui-skills

GitHub UI Skills

Opinionated constraints for building GitHub-style interfaces with AI agents.

When to Apply

Reference these guidelines when:

• Building dark-mode interfaces
• Creating GitHub-inspired design systems
• Implementing UIs with Inter font and 4px grid

Colors

• MUST use dark backgrounds (lightness < 20) for primary surfaces - detected lightness: 12
• MUST use #10131A as page background (surface-base)
• MUST use #030036 for primary actions and focus states (accent)
• SHOULD reduce color palette (currently 23 colors detected)
• MUST maintain text contrast ratio of at least 4.5:1 for accessibility

Semantic Tokens

Token	HEX	RGB	Usage
surface-base	#10131A	rgb(16,19,26)	Page background
surface-raised	#11122F	rgb(17,18,47)	Cards, modals, raised surfaces
surface-overlay	#186D29	rgb(24,109,41)	Overlays, tooltips, dropdowns
text-primary	#878A91	rgb(135,138,145)	Headings, body text
text-secondary	#74777E	rgb(116,119,126)	Secondary, muted text
text-tertiary	#525C71	rgb(82,92,113)	Additional text
border-default	#1A1835	rgb(26,24,53)	Subtle borders, dividers
success	#A3D4AD	rgb(163,212,173)	Success states, confirmations
accent	#030036	rgb(3,0,54)	Primary actions, links, focus

Typography

• MUST use Inter as primary font family
• SHOULD use single font family for consistency
• MUST use 53px / 700 for primary headings
• MUST use 29px / 400 for body text
• MUST limit font weights to: regular, bold, light
• MUST use text-balance for headings and text-pretty for body text
• SHOULD use tabular-nums for numeric data
• NEVER modify letter-spacing unless explicitly requested

Text Styles

Style	Font	Size	Weight	Color	Count
heading-1	Inter	53px	700	#E3E4EA	1
body	Inter	29px	400	#606A7A	1
text-18px	Inter	18px	400	#A7A8BF	1
text-16px	Inter	16px	300	#989BA2	1
text-15px	Inter	15px	300	#3F4249	1
text-15px	Inter	15px	400	#7F848A	1
text-15px	Inter	15px	400	#B5B6C4	1
text-15px	Inter	15px	400	#A3D4AD	1
text-15px	Inter	15px	400	#6B6B71	1
text-15px	Inter	15px	400	#9796B1	1

Typography Reference

Font Families:

• Inter (used 54x)

Font Sizes: 4px, 5px, 9px, 10px, 11px, 12px, 13px, 14px, 15px, 16px, 18px, 29px, 53px

Spacing

• MUST use 4px grid for spacing
• SHOULD use spacing from scale: 2px, 3px, 4px, 5px, 6px, 8px, 11px, 14px
• SHOULD use 5px as default gap between elements
• NEVER use arbitrary spacing values (use design scale)
• SHOULD maintain consistent padding within containers

Borders

• MUST use border-radius from scale: 3px, 4px, 5px, 9px, 15px, 22px, 29px
• SHOULD use 22px+ radius for pill-shaped elements
• SHOULD limit border widths to: 1px, 2px, 3px, 4px
• SHOULD use 3px as default border-radius
• NEVER use arbitrary border-radius values (use design scale)
• SHOULD use subtle borders (1px) for element separation

Border Radius Reference

Scale: 3px, 4px, 5px, 9px, 15px, 22px, 29px

Layout

• MUST design for 1920px base viewport width
• SHOULD use consistent element widths: 10px, 9px, 11px, 28px, 21px
• SHOULD maintain text-heavy layout with clear hierarchy
• NEVER use h-screen, use h-dvh for full viewport height
• MUST respect safe-area-inset for fixed elements
• SHOULD use size-* for square elements instead of w-* + h-*

Detected Layout Patterns

• Main Content: width: 1920px, height: 1080px
• Main Content: width: 1920px, height: 1004px
• Header: height: 64px

Components

• MUST use 0px height for input fields

Buttons

Variant	Background	Text	Border	Height	Radius
Ghost	transparent	#B5B6C4	none	-	-

Inputs

• Height: 0px

Interactive States

Focus

• MUST use 2px outline with accent color (#030036)
• MUST use 2px outline-offset
• NEVER remove focus indicators

Hover

• Buttons (primary): lighten background by 10%
• Buttons (secondary): use #11122F background
• List items: use #11122F background

Disabled

• MUST use opacity: 0.5
• MUST use cursor: not-allowed

Interaction

• MUST use an AlertDialog for destructive or irreversible actions
• SHOULD use structural skeletons for loading states
• MUST show errors next to where the action happens
• NEVER block paste in input or textarea elements
• MUST add an aria-label to icon-only buttons

Animation

• NEVER add animation unless it is explicitly requested
• MUST animate only compositor props (transform, opacity)
• NEVER animate layout properties (width, height, top, left, margin, padding)
• SHOULD use ease-out on entrance animations
• NEVER exceed 200ms for interaction feedback
• SHOULD respect prefers-reduced-motion

Performance

• NEVER animate large blur() or backdrop-filter surfaces
• NEVER apply will-change outside an active animation
• NEVER use useEffect for anything that can be expressed as render logic