@open-pencil/dom-css

DOM and CSS projection utilities for OpenPencil.

This package is the compatibility layer between OpenPencil's scene graph and DOM-shaped design documents. It is intentionally separate from @open-pencil/core so browser/CSS parser integrations can evolve without adding DOM dependencies to the renderer and editor core.

Installation

bun add @open-pencil/dom-css @open-pencil/core

@open-pencil/core is a peer dependency because @open-pencil/dom-css projects to and from OpenPencil scene graphs. Consumers that only parse/serialize DesignDOM still need the peer installed for the package entrypoint.

Package-local checks

This package can be validated independently from the app shell:

cd packages/dom-css
bun run test
bun run typecheck
bun run check

Package scripts:

bun run test — package-local Bun tests for runtime, conversion, and Tailwind APIs
bun run typecheck — type-checks src, tests, and package scripts
bun run build — builds the distributable dist entrypoint
bun run smoke:dist — imports the built dist bundle and exercises the public API
bun run check — runs typecheck, tests, build, and dist smoke in sequence

The repository also keeps integration/oracle coverage under tests/engine/dom-css and tests/e2e/dom-css. The package-local suite focuses on the library's public API, while the repo-level E2E suite verifies browser getComputedStyle() parity through Playwright.

Runtime model

Use the browser runtime as the high-fidelity source of truth whenever a DOM is available. It uses native parsing and getComputedStyle() inside an isolated sandbox:

import { createBrowserCSSRuntime } from '@open-pencil/dom-css'

const runtime = createBrowserCSSRuntime({ sandbox: 'iframe' })
const document = runtime.parseHTML('<article class="card">OpenPencil</article>')
const styled = await runtime.computeStyles(document, '.card { width: calc(10rem + 16px); }')

The headless runtime is useful for Bun/Node tests, CLI flows, and fast approximate conversion. It supports common selectors, inheritance, shorthands, CSSOM grouping rules, and simple variable/calc values, but it is not a browser replacement.

import { createHeadlessCSSRuntime } from '@open-pencil/dom-css'

const runtime = createHeadlessCSSRuntime()

HTML/CSS to scene graph

The convenience helpers run the full pipeline:

import { htmlToSceneGraph } from '@open-pencil/dom-css'

const graph = await htmlToSceneGraph(
  '<article class="card"><h1>OpenPencil</h1></article>',
  {
    cssText: '.card { display: flex; gap: 12px; width: 320px; padding: 24px; }'
  }
)

For DesignDOM output without creating a scene graph, use htmlToDesignDocument().

Tailwind pipeline

Tailwind classes flow through Tailwind's own compiler, then through the CSS runtime:

import { tailwindHTMLToSceneGraph } from '@open-pencil/dom-css'

const classes = ['flex', 'w-80', 'p-6', 'rounded-xl', 'bg-white']
const graph = await tailwindHTMLToSceneGraph(
  `<article class="${classes.join(' ')}">OpenPencil</article>`,
  classes
)

compileTailwindCSS() remains available when callers want to manage runtime selection themselves.

Current scope

DOM-shaped DesignDocument / DesignElement types
Browser-backed runtime adapter for native HTML parsing, serialization, and computed-style extraction
Headless runtime adapter with parse5 HTML parsing and CSSOM-backed style computation for basic selectors, nested CSSOM rules, cascade order, inheritance, common shorthands, and simple custom-property/calc values
SceneGraph ⇄ DesignDOM conversion for simple HTML/CSS-shaped layouts
Tailwind v4 compiler adapter
Browser oracle fixtures for CSS variables, calc(), modern color output, and Tailwind utility output

Roadmap

Expand reusable fixtures: inputs, badges, nav/menu rows, dialog shells, and richer cards
Map more computed CSS properties to scene graph fields: richer shadows, typography details, overflow, constraints, borders, and grid once OpenPencil's grid support matures
Improve SceneGraph → CSS export so generated HTML/CSS is useful for JSX, Tailwind, and web export
Keep @open-pencil/dom-css stable before splitting lower-level file-format packages such as future @open-pencil/kiwi and @open-pencil/fig

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