Anthropic UI Skills
Opinionated constraints for building Anthropic-style interfaces with AI agents.
When to Apply
Reference these guidelines when:
- •Building light-mode interfaces
- •Creating Anthropic-inspired design systems
- •Implementing UIs with Inter font and 4px grid
Colors
- •SHOULD use light backgrounds for primary surfaces
- •MUST use
#ECE9E0as 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 | #ECE9E0 | rgb(236,233,224) | Page background |
surface-raised | #DBD1C0 | rgb(219,209,192) | Cards, modals, raised surfaces |
surface-overlay | #0F0F10 | rgb(15,15,16) | Overlays, tooltips, dropdowns |
text-primary | #625F59 | rgb(98,95,89) | Headings, body text |
text-secondary | #9F9F9C | rgb(159,159,156) | Secondary, muted text |
text-tertiary | #454036 | rgb(69,64,54) | Additional text |
Typography
- •MUST use
Interas primary font family - •SHOULD use single font family for consistency
- •MUST use
68px/700for primary headings - •MUST use
33px/semi_boldfor body text - •SHOULD reduce font weights (currently 5 detected)
- •MUST use
text-balancefor headings andtext-prettyfor body text - •SHOULD use
tabular-numsfor numeric data - •NEVER modify letter-spacing unless explicitly requested
Text Styles
| Style | Font | Size | Weight | Color | Count |
|---|---|---|---|---|---|
heading-1 | Inter | 68px | 700 | #201F1D | 1 |
body | Inter | 33px | semi_bold | #35312A | 1 |
text-23px | Inter | 23px | 500 | #403D37 | 1 |
text-21px | Inter | 21px | 400 | #3D362C | 1 |
text-21px | Inter | 21px | 400 | #3B352B | 1 |
text-20px | Inter | 20px | 400 | #494237 | 1 |
text-17px | Inter | 17px | 500 | #423F3B | 1 |
text-16px | Inter | 16px | 400 | #454036 | 1 |
text-14px | Inter | 14px | 500 | #3F3931 | 1 |
text-14px | Inter | 14px | 400 | #A2A3A0 | 1 |
Typography Reference
Font Families:
- •
Inter(used 16x)
Font Sizes: 10px, 11px, 14px, 16px, 17px, 20px, 21px, 23px, 33px, 68px
Spacing
- •MUST use 4px grid for spacing
- •SHOULD use spacing from scale: 3px, 4px, 5px, 6px
- •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, 15px
- •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, 15px
Layout
- •MUST design for 1920px base viewport width
- •SHOULD use consistent element widths: 10px, 18px, 146px, 579px
- •SHOULD maintain text-heavy layout with clear hierarchy
- •NEVER use
h-screen, useh-dvhfor full viewport height - •MUST respect
safe-area-insetfor fixed elements - •SHOULD use
size-*for square elements instead ofw-*+h-*
Detected Layout Patterns
- •Main Content: width: 1920px, height: 1004px
- •Main Content: width: 1920px, height: 673px
Components
- •MUST use
0pxheight for input fields
Buttons
| Variant | Background | Text | Border | Height | Radius |
|---|---|---|---|---|---|
| Ghost | transparent | #9F9F9C | none | - | - |
Inputs
- •Height:
0px
Interactive States
Focus
- •MUST use
2pxoutline with accent color (#5E6AD2) - •MUST use
2pxoutline-offset - •NEVER remove focus indicators
Hover
- •Buttons (primary): lighten background by 10%
- •Buttons (secondary): use
#DBD1C0background - •List items: use
#DBD1C0background
Disabled
- •MUST use
opacity: 0.5 - •MUST use
cursor: not-allowed
Interaction
- •MUST use an
AlertDialogfor destructive or irreversible actions - •SHOULD use structural skeletons for loading states
- •MUST show errors next to where the action happens
- •NEVER block paste in
inputortextareaelements - •MUST add an
aria-labelto 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-outon entrance animations - •NEVER exceed
200msfor interaction feedback - •SHOULD respect
prefers-reduced-motion
Performance
- •NEVER animate large
blur()orbackdrop-filtersurfaces - •NEVER apply
will-changeoutside an active animation - •NEVER use
useEffectfor anything that can be expressed as render logic