Matter UI Skills

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

When to Apply

Reference these guidelines when:

• Building dark-mode interfaces

• Creating Matter-inspired design systems

• Implementing UIs with Inter font and 4px grid

Colors

• MUST use dark backgrounds (lightness < 20) for primary surfaces - detected lightness: 0

• MUST use #000000 as page background (surface-base )

• MUST use #5560EC for primary actions and focus states (accent )

• SHOULD reduce color palette (currently 19 colors detected)

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

Semantic Tokens

Token HEX RGB Usage

surface-base

#000000 rgb(0,0,0) Page background

surface-raised

#CFE3F9 rgb(207,227,249) Cards, modals, raised surfaces

surface-overlay

#8DBDF7 rgb(141,189,247) Overlays, tooltips, dropdowns

text-primary

#627EA1 rgb(98,126,161) Headings, body text

text-2

#8C9BAB rgb(140,155,171) Additional text

text-secondary

#888888 rgb(136,136,136) Secondary, muted text

border-default

#D4E5F8 rgb(212,229,248) Subtle borders, dividers

accent

#5560EC rgb(85,96,236) Primary actions, links, focus

destructive

#200D11 rgb(32,13,17) Error states, delete actions

Typography

• MUST use Inter as primary font family

• SHOULD use single font family for consistency

• MUST use 81px / 700 for primary headings

• MUST use 35px / 700 for body text

• SHOULD reduce font weights (currently 6 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 81px 700 #F0F0F0 1

body

Inter 35px 700 #818181 1

text-32px

Inter 32px semi_bold #747474 1

text-26px

Inter 26px extra_bold #8C8C8C 1

text-24px

Inter 24px 700 #848484 1

text-21px

Inter 21px semi_bold #494949 1

text-20px

Inter 20px 500 #515151 1

text-19px

Inter 19px 400 #666666 1

text-16px

Inter 16px 400 #3C3C3C 1

text-15px

Inter 15px 400 #525252 1

Typography Reference

Font Families:

• Inter (used 32x)

Font Sizes: 8px, 9px, 10px, 11px, 12px, 13px, 14px, 15px, 16px, 19px, 20px, 21px, 24px, 26px, 32px, 35px, 81px

Spacing

• MUST use 4px grid for spacing

• SHOULD use spacing from scale: 1px, 2px, 4px, 5px, 6px, 7px, 9px, 10px

• SHOULD use 2px 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: 0px, 1px, 10px, 15px

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

• SHOULD use 1px 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: 0px, 1px, 10px, 15px

Layout

• MUST design for 1920px base viewport width

• SHOULD use consistent element widths: 13px, 102px, 38px, 37px, 14px

• 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

• Header: height: 58px

• Main Content: width: 1920px, height: 1025px

• Main Content: width: 1920px, height: 1023px

• Header: height: 59px

Components

Buttons

Variant Background Text Border Height Radius

Ghost transparent #8C9BAB none

Interactive States

Focus

• MUST use 2px outline with accent color (#5560EC )

• MUST use 2px outline-offset

• NEVER remove focus indicators

Hover

• Buttons (primary): lighten background by 10%

• Buttons (secondary): use #CFE3F9 background

• List items: use #CFE3F9 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