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