HTML Input

Forme 0.14 adds a second front door to the engine: @formepdf/html renders HTML + print CSS to PDF through the same Rust/WASM engine that renders JSX components. No headless browser, no Chromium cold start.

# CLI — zero config
npx @formepdf/html invoice.html -o invoice.pdf

# with a separate stylesheet, page setup, and fonts
npx @formepdf/html report.html --css print.css --page-size Letter --margin 36 --font "Inter=Inter.ttf"

// Library
import { renderHtml } from "@formepdf/html";

const { pdf, warnings } = await renderHtml(html, { css, fonts });

The subset — the constitution

This is a deliberately documented subset of HTML/CSS, in the spirit of Satori — but page-native. Everything supported is listed below and tested. Everything outside the subset lands in the warnings list at render time, named, with a remedy where one exists. Nothing fails silently.

Paged media — the point of the whole thing

Supported	Not supported (warned)
`@page` `size` (named, dimensions, `landscape`) and `margin`	`@page` `bleed` / `marks`
`@page :first` — different margins, headers off the title page	`:left` / `:right` page variants
Margin boxes (`@top-center`, `@bottom-right`, …) for running headers/footers
Page counters — `counter(page)` and `counter(pages)`
`break-before` / `break-after` / `break-inside: avoid` (+ legacy `page-break-*` aliases)
`orphans` / `widows`
`@media` media-type evaluation — `print` is the native media type; feature queries evaluate against the page content box	`prefers-color-scheme`, `not` conditions (excluded with a named warning)
`<thead>` repetition across page breaks; table-cell overflow preservation

Elements

Supported	Not supported
Block containers: `div`, `section`, `article`, `header`, `footer`, `main`, `aside`, `nav`, `address`, `figure`, `blockquote`, `hr`	JavaScript of any kind (`<script>` skipped)
`h1`–`h6`, `p`, `br`	`<canvas>`, `<video>`, `<audio>`, `<iframe>`, forms
Inline: `span`, `b`/`strong`, `i`/`em`, `u`, `s`/`del`, `a`, `small`, `code`, `mark`, `sub`, `sup`	Inline `<img>` mid-paragraph
Tables: `table`, `thead`, `tbody`, `tfoot`, `tr`, `td`, `th` + `colspan`/`rowspan`
Lists: `ul`, `ol` (+ `start`), `li`
`img` (block-level) — data URIs and local files	External `http(s)` image fetching
`<style>` blocks; the CLI inlines local `<link rel="stylesheet">`	Remote stylesheets — never fetched, warned with the href and remedy

Selectors

Supported	Not supported (selector skipped, warned)
Type, class, id, universal; compounds	Pseudo-elements (`::before`, `::after`)
Descendant and child combinators; grouping	Attribute selectors, sibling combinators
`:first-child`, `:last-child`, `:nth-child(even\|odd\|an+b)`	`:only-child` and remaining tree pseudo-classes
`:first-of-type`, `:last-of-type`, `:nth-of-type`, `:nth-last-child`, `:nth-last-of-type`	Interaction pseudo-classes (`:hover`) — permanent: print has no hover
Full cascade with `!important`

Properties

The full property table lives in the package README — margins with CSS margin collapsing, borders (solid/dashed/dotted with Chrome-matched dash metrics), border-collapse emulation, min/max width constraints (the centered-column idiom works), font fallback chains, text-align: justify with real Knuth-Plass distribution, text-transform, letter-spacing, vertical-align on cells, flexbox, and relative/absolute positioning. Notable exclusions, all warned by name: float, CSS Grid, CSS variables, position: fixed/sticky, transforms, gradients, @font-face fetching (use options.fonts / --font — see the web-fonts migration recipe).

The warnings contract

$ npx @formepdf/html letterhead.html -o letterhead.pdf
warning: unsupported property: text-transform-origin

Every warning names the thing it skipped: the property, the selector, the stylesheet href, the @font-face family. If a render is silent, the document used only the subset — and what you got is what the subset defines.

Getting Started

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The subset — the constitution

Paged media — the point of the whole thing

Elements

Selectors

Properties

The warnings contract

Migrating

​The subset — the constitution

​Paged media — the point of the whole thing

​Elements

​Selectors

​Properties

​The warnings contract

​Migrating

The subset — the constitution

Paged media — the point of the whole thing

Elements

Selectors

Properties

The warnings contract

Migrating