OpenAI UI Skills

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

When to Apply

Reference these guidelines when:

• Building light-mode interfaces

• Creating OpenAI-inspired design systems

• Implementing UIs with Inter font and 4px grid

Colors

• SHOULD use light backgrounds for primary surfaces

• MUST use #FFFFFF as page background (surface-base )

• SHOULD limit color palette to 8 distinct colors

• MUST maintain text contrast ratio of at least 4.5:1 for accessibility

Semantic Tokens

Token HEX RGB Usage

surface-base

#FFFFFF rgb(255,255,255) Page background

text-primary

#525252 rgb(82,82,82) Headings, body text

text-secondary

#747474 rgb(116,116,116) Secondary, muted text

text-tertiary

#8A8A8A rgb(138,138,138) Additional text

border-default

#C9C0BB rgb(201,192,187) Subtle borders, dividers

Typography

• MUST use Inter as primary font family

• SHOULD use single font family for consistency

• MUST use 24px / semi_bold for primary headings

• MUST use 14px / 400 for body text

• MUST limit font weights to: regular, semi_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 24px semi_bold #212121 1

heading-2

Inter 24px semi_bold #222222 1

body

Inter 14px 400 #8F8F8F 1

body-secondary

Inter 13px 400 #525252 2

body-secondary

Inter 13px 400 #5B5B5B 1

body-secondary

Inter 13px 400 #565656 1

body-secondary

Inter 11px 400 #8A8A8A 1

body-secondary

Inter 11px 400 #8D8D8D 1

text-10px

Inter 10px 400 #5C5C5C 2

text-10px

Inter 10px 400 #575757 2

Typography Reference

Font Families:

• Inter (used 19x)

Font Sizes: 7px, 10px, 11px, 13px, 14px, 24px

Spacing

• MUST use 4px grid for spacing

• SHOULD use spacing from scale: 4px, 5px, 6px, 7px, 10px, 11px, 31px, 32px

• SHOULD use 4px 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: 16px, 18px, 19px, 22px

• SHOULD use 22px+ radius for pill-shaped elements

• MUST use 1px border width consistently

• SHOULD use 19px 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: 16px, 18px, 19px, 22px

Layout

• MUST design for 1920px base viewport width

• SHOULD use 202px for sidebar width

• SHOULD use consistent element widths: 8px, 21px, 14px, 61px, 36px

• 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

• Sidebar: width: 202px, position: left

Components

• MUST use 0px height for input fields

Buttons

Variant Background Text Border Height Radius

Ghost transparent #8A8A8A none

Inputs

• Height: 0px

Interactive States

Focus

• MUST use 2px outline with accent color (#5E6AD2 )

• MUST use 2px outline-offset

• NEVER remove focus indicators

Hover

• Buttons (primary): lighten background by 10%

• Buttons (secondary): use surface-raised background

• List items: use surface-raised 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