Arc UI Skills

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

When to Apply

Reference these guidelines when:

• Building light-mode interfaces

• Creating Arc-inspired design systems

• Implementing UIs with Inter font and 4px grid

Colors

• SHOULD use light backgrounds for primary surfaces

• MUST use #E4E4E4 as page background (surface-base )

• MUST use #6FADE2 for primary actions and focus states (accent )

• SHOULD reduce color palette (currently 26 colors detected)

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

Semantic Tokens

Token HEX RGB Usage

surface-base

#E4E4E4 rgb(228,228,228) Page background

surface-raised

#1B00B5 rgb(27,0,181) Cards, modals, raised surfaces

surface-overlay

#FEFEFD rgb(254,254,253) Overlays, tooltips, dropdowns

text-primary

#BFAFEA rgb(191,175,234) Headings, body text

text-secondary

#513EA3 rgb(81,62,163) Secondary, muted text

text-tertiary

#E0DCEA rgb(224,220,234) Additional text

border-default

#1902BE rgb(25,2,190) Subtle borders, dividers

accent

#6FADE2 rgb(111,173,226) Primary actions, links, focus

warning

#FEFEFD rgb(254,254,253) Warning states, cautions

Typography

• MUST use Inter as primary font family

• SHOULD use single font family for consistency

• MUST use 53px / 700 for primary headings

• MUST use 22px / 500 for body text

• SHOULD reduce font weights (currently 5 detected)

• 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 #E4E3EF 1

text-36px

Inter 36px 700 #2D2C2B 1

body

Inter 22px 500 #C7C7C7 1

text-19px

Inter 19px 400 #666664 1

text-14px

Inter 14px semi_bold #E0DCEA 1

text-13px

Inter 13px 400 #37556A 1

text-13px

Inter 13px 300 #C0C2C2 1

text-13px

Inter 13px 400 #AEACF0 1

text-12px

Inter 12px 400 #BFAFEA 1

text-12px

Inter 12px 400 #513EA3 1

Typography Reference

Font Families:

• Inter (used 28x)

Font Sizes: 5px, 6px, 8px, 9px, 10px, 11px, 12px, 13px, 14px, 19px, 22px, 36px, 53px

Spacing

• MUST use 4px grid for spacing

• SHOULD use spacing from scale: 1px, 2px, 3px, 4px, 5px, 6px, 7px, 10px

• 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: 2px, 3px, 4px, 5px, 6px, 7px, 8px, 9px, 21px, 22px

• SHOULD use 21px+ radius for pill-shaped elements

• SHOULD limit border widths to: 1px, 2px

• SHOULD use 7px 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: 2px, 3px, 4px, 5px, 6px, 7px, 8px, 9px, 21px, 22px

Layout

• MUST design for 1920px base viewport width

• SHOULD use consistent element widths: 69px, 11px, 10px, 70px, 15px

• 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: 602px

• Main Content: width: 1920px, height: 613px

• Header: height: 99px

Components

Buttons

Variant Background Text Border Height Radius

Ghost transparent #BFAFEA none

Interactive States

Focus

• MUST use 2px outline with accent color (#6FADE2 )

• MUST use 2px outline-offset

• NEVER remove focus indicators

Hover

• Buttons (primary): lighten background by 10%

• Buttons (secondary): use #1B00B5 background

• List items: use #1B00B5 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