Scalar Design System

Scalar Design System

This skill is Scalar's design system, distilled for two jobs:

1. Designing Scalar UI in Paper (code-to-design) — so a design uses Scalar's real palette, type, spacing, and component shapes from the first stroke, with no invented "design brief."
2. Turning a Paper design into code (design-to-code) — so the output maps back to the correct --scalar-* variables, Tailwind classes, and @scalar/components.

It complements the code-to-design and design-to-code plugin skills; this one supplies the Scalar-specific knowledge they lack.

Prerequisite for Paper work: Paper Desktop must be running with a file open. If the Paper MCP connection fails, ask the user to open Paper Desktop first.

The values below are a curated snapshot of the default theme — enough to design and implement directly. For the full variable catalog, all 13 theme presets, and the complete component list, read the reference files:

• references/tokens.md — every --scalar-* variable, the Tailwind mapping, and all theme presets.
• references/components.md — all 34 components, their variants/props, and the subpath import map.
• references/paper.md — bidirectional Paper ↔ Scalar mapping tables for round-tripping designs.

Brand essentials

Scalar's look is a clean, modern developer-tool aesthetic: high-contrast typography, restrained color, hairline borders, and small radii. Treat it as a product/clarity system, not a marketing/expressive one.

• Type: Inter for UI and prose, JetBrains Mono for code.
• Accent: #0099ff (one deliberate accent; everything else is neutral).
• Mode: light mode by default (#fff ground, #1b1b1b text).
• Borders: hairline 0.5px, color #dfdfdf.
• Radii: small — 3px default, 6px large, 8px extra-large.
• Shape: information lives directly on surfaces; reserve cards/elevation for genuine grouping.

Foundations

• Scoping: every Scalar style lives under the .scalar-app class. Any markup must be inside an element with class="scalar-app".
• Light / dark: a .light-mode or .dark-mode class on a container selects the value set. Default to .light-mode.
• Layers: themes load in two CSS layers — scalar-base (base variables + default theme) and scalar-theme (preset overrides). Unlayered CSS overrides both.

Design tokens (default theme)

Reference --scalar-* variables in CSS; in components, prefer the Tailwind classes (next section).

Color — text (--scalar-color-*)

Color — background (--scalar-background-*)

Borders & shadows

• --scalar-border-color — #dfdfdf (light) / #2d2d2d (dark); --scalar-border-width — 0.5px.
• --scalar-shadow-1 (subtle), --scalar-shadow-2 (lifted).

Semantic colors (--scalar-color-{green,red,yellow,blue,orange,purple}, plus --scalar-color-danger / --scalar-color-alert and matching --scalar-background-*). Light: green #069061, red #ef0006, yellow #edbe20, blue #0082d0, orange #ff5800, purple #5203d1.

Radii: --scalar-radius 3px, --scalar-radius-md 3px, --scalar-radius-lg 6px, --scalar-radius-xl 8px, --scalar-radius-2xl 12px, --scalar-radius-3xl 16px, --scalar-radius-full pill. All derive from --scalar-radius, so overriding it on :root rescales every corner, and 0 makes the interface square. Everything except -full clamps to --scalar-radius-max (20px) so a large radius cannot swallow a container's content. Reach for --scalar-radius-md rather than --scalar-radius on anything that holds content.

Typography

• Content sizes: heading-1 24px, heading-2 20px, heading-3–6 16px, paragraph 16px, small 14px, mini 13px, micro 12px.
• UI app sizes: --scalar-font-size-1…7 = 21, 16, 14, 13, 12, 12, 10 px.
• Line heights: --scalar-line-height-1…5 = 32, 24, 20, 18, 16 px.
• Weights: regular 400, semibold 500, bold 600.

Tailwind class mapping

Scalar maps --scalar-* variables onto a custom Tailwind theme. In components, use these classes rather than raw variables. Source of truth: @scalar/themes/tailwind.css.

• Background: bg-b-1, bg-b-1.5, bg-b-2, bg-b-3, bg-b-accent, bg-b-btn, bg-b-tooltip, bg-b-danger, bg-b-alert.
• Text: text-c-1, text-c-2, text-c-3, text-c-accent, text-c-ghost, text-c-disabled, text-c-btn, text-c-tooltip, text-c-danger, text-c-alert.
• Themed: text-green / bg-green, plus red, yellow, blue, orange, purple.
• Border: border (uses --scalar-border-color, default width 0.5px); shadow-border for an inset hairline.
• Shadow: shadow / shadow-md (shadow-1), shadow-lg (shadow-2), shadow-sm.
• Radius: rounded & rounded-md (3px), rounded-lg (6px), rounded-xl (8px), rounded-2xl (12px), rounded-3xl (16px), rounded-full (pill). No rounded-sm.
• Type: font-sans (Inter), font-code (JetBrains Mono); sizes text-3xs 10, text-xxs/text-xs 12, text-sm 13, text-base 14, text-lg 16, text-xl 21; weights font-normal 400, font-medium 500, font-bold 600.
• Spacing: base unit is 4px, so p-1 = 4px, p-2 = 8px, gap-3 = 12px, etc. h-header = 48px.
• Breakpoints: xs 400, sm 600, md 800, lg 1000, xl 1200.

Components — @scalar/components

A Vue 3 library (34 components) scoped to .scalar-app, styled with the Tailwind classes above via cva variants, and customizable through Tailwind class overrides (useBindCx). Import from the subpath, not the barrel:

import { ScalarButton } from '@scalar/components/button'
import { ScalarIconAcorn } from '@scalar/icons'

Headline components (full list in references/components.md):

• Buttons & inputs: ScalarButton (variant solid | outlined | ghost | gradient | danger; size xs | sm | md), ScalarIconButton, ScalarTextInput, ScalarTextArea, ScalarToggle, ScalarCheckbox, ScalarSearchInput, ScalarFileUpload.
• Selection / floating: ScalarCombobox, ScalarListbox, ScalarDropdown, ScalarPopover, ScalarTooltip (all positioned with Floating UI).
• Overlays: ScalarModal (sizes xxs–full).
• Layout / nav: ScalarHeader (+ ScalarHeaderColumn), ScalarSidebar, ScalarMenu.
• Content: ScalarCard, ScalarCodeBlock, ScalarMarkdown, ScalarForm, ScalarLoading.

Icons come from @scalar/icons (1,500+ Phosphor icons as ScalarIcon<Name> components). Size with size-* (size-4, size-5) and color with text-*. ScalarButton takes an :icon prop.

Working in Paper

code-to-design — build Scalar UI in Paper

Paper writes literal HTML/CSS to the canvas with px sizes and hex colors, so translate Scalar tokens into concrete values:

• Ground #fff, text #1b1b1b (secondary #757575), accent #0099ff, borders 0.5px #dfdfdf, radii 3–8px.
• Inter for everything except code (JetBrains Mono); body text 16px, small 14px.
• Spacing on a 4px grid (4, 8, 12, 16, 24…).
• Default to light mode. Mirror the real component shapes (buttons, cards, sidebar rows) using these values.
• Because the design system is specified here, skip Paper's invented design brief and design directly in Scalar's system.

design-to-code — turn a Paper design into Scalar code

1. Extract exact values from Paper with get_jsx / get_computed_styles / get_fill_image — never read sizes or colors off a screenshot.
2. Map values back to tokens / Tailwind: e.g. #0099ff → --scalar-color-accent / text-c-accent; #fff → bg-b-1; #1b1b1b → text-c-1; 0.5px #dfdfdf border → border; 3px radius → rounded; 16px Inter → text-lg font-sans. See references/paper.md for the full table.
3. Map elements to components: button → ScalarButton (pick variant + size); card → ScalarCard; menu/select → ScalarDropdown / ScalarListbox / ScalarCombobox; dialog → ScalarModal; icon → an @scalar/icons ScalarIcon*. Import each from its subpath.
4. Where the component docs are (to confirm a component, its props, and variants):
   • @scalar/components package.json exports — the subpath → component map.
   • The bundled TypeScript declarations (*.d.ts) shipped with each component — props, variants, and JSDoc.
   • The @scalar/components Storybook — live variants and controls.
5. Output conventions: wrap rendered output in .scalar-app; override styles with Tailwind classes via useBindCx (do not hand-write CSS); follow the vue-components skill for component code style.

Source of truth

When exact or current values matter, go to the package that owns them — read these from node_modules/<package>/ (or the package on npm):

• Tokens & theming — @scalar/themes: the compiled variables and the Tailwind @theme mapping ship as @scalar/themes/style.css and @scalar/themes/tailwind.css; the JS API (getThemeStyles, presets, themeIds, ThemeId) is exported from the package root (@scalar/themes).
• Components — @scalar/components: the subpath import map is in the package's package.json exports; the full export list and per-component props/variants live in the bundled type declarations (*.d.ts).
• Icons — @scalar/icons: the ScalarIcon* set is exported from the package root (@scalar/icons).