Compatibility

vellora supports a strict-by-default, documented HTML/CSS subset built for generated document HTML. Inputs such as invoices, receipts, boletos, and notifications are representative scenarios, not domain entities or special render modes. In strict mode (the default), out-of-subset input is rejected with a VelloraUnsupportedError rather than rendered incorrectly.

The canonical subset table

The exact list of supported and unsupported HTML elements and CSS properties is maintained in a single source of truth so it can never drift: the repository's COMPATIBILITY.md.

This page intentionally does not duplicate that table — consult COMPATIBILITY.md for the authoritative, up-to-date matrix.

How strictness works

• strict: true (default) — your HTML/CSS is validated against the subset and never mutated. Anything outside the subset throws VelloraUnsupportedError, which carries a located diagnostic (feature, line, col, hint) so you can find and fix the offending markup.
• @vellora/lint — diagnose(html) reports subset issues at authoring/CI time, and fix(html) rewrites common mechanical violations deterministically.
• strict: false — the public renderer runs the same @vellora/lint fixers first to bring common out-of-subset input back inside the supported set before rendering.
• vellora lint / vellora fix — CLI wrappers for the same lint library when you want file-based checks or in-place rewrites.
• Assets are explicit. Images come from data: URLs or the images map; fonts come from the fonts option. Native rendering does not fetch remote assets. See Images and Fonts.

import { renderPdf, VelloraUnsupportedError } from "vellora";

try {
  await renderPdf("<div><script>alert(1)</script></div>");
} catch (err) {
  if (err instanceof VelloraUnsupportedError) {
    console.log(`Rejected: feature="${err.feature}" — ${err.hint}`);
  }
}

See the API Reference for the full error surface.