Resend UI Skills

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

When to Apply

Reference these guidelines when:

• Building dark-mode interfaces

• Creating Resend-inspired design systems

• Implementing UIs with Inter font and 4px grid

Colors

• MUST use dark backgrounds (lightness < 20) for primary surfaces - detected lightness: 2

• MUST use #060606 as page background (surface-base )

• SHOULD limit color palette to 5 distinct colors

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

Semantic Tokens

Token HEX RGB Usage

surface-base

#060606 rgb(6,6,6) Page background

surface-raised

#1D1D1D rgb(29,29,29) Cards, modals, raised surfaces

text-primary

#6E6E6E rgb(110,110,110) Headings, body text

text-2

#BBBBBB rgb(187,187,187) Additional text

border-default

#191919 rgb(25,25,25) Subtle borders, dividers

Typography

• MUST use Inter as primary font family

• SHOULD use single font family for consistency

• MUST use 88px / 700 for primary headings

• MUST use 18px / 400 for body text

• MUST limit font weights to: bold, regular, medium

• 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 88px 700 #C8C8C8 1

body

Inter 18px 400 #646464 1

body-secondary

Inter 17px 500 #BFBFBF 1

text-15px

Inter 15px 400 #6A6A6A 1

text-14px

Inter 14px 400 #666666 1

text-14px

Inter 14px 400 #626262 1

text-14px

Inter 14px 400 #646464 1

caption

Inter 13px 400 #6E6E6E 1

label

Inter 12px 500 #BBBBBB 1

label

Inter 11px 400 #B6B6B5 1

Typography Reference

Font Families:

• Inter (used 13x)

Font Sizes: 11px, 12px, 13px, 14px, 15px, 17px, 18px, 88px

Spacing

• MUST use 4px grid for spacing

• SHOULD use spacing from scale: 4px, 5px, 13px, 19px, 22px, 60px

• 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: 15px

• SHOULD limit border widths to: 2px, 3px

• SHOULD use 15px 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: 15px

Layout

• MUST design for 1920px base viewport width

• SHOULD use consistent element widths: 8px

• 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

• Main Content: width: 1920px, height: 963px

• Header: height: 57px

Components

Buttons

Variant Background Text Border Height Radius

Ghost transparent #BBBBBB none

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 #1D1D1D background

• List items: use #1D1D1D 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