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

github-ui-skills

NPX Install

Tags

SKILL.md Content