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