Brand font `@font-face` paths resolve incorrectly in Reveal.js theme

Open

#14,284 opened on Mar 30, 2026 0 comments 3 reactions 0 assignees View on GitHub

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Assessment

Difficulty: 3/5
Estimated time: 1-2 days
Newbie friendliness: 52/100

Issue type: Bug
Clarity: Mostly clear
Activity status: Quiet
Tech stack: css, javascript
Domain: frontend, web-dev

Research direction

Start by reproducing the issue with the provided _brand.yml and example.qmd, then inspect the generated CSS under {output}_files/libs/revealjs/dist/theme/. The fix is complete when Reveal.js font URLs resolve from the project root and render without resource warnings or missing embedded fonts.

Written by the indexing model from the issue text.

Description

brand bug revealjs

Bug description

When using _brand.yml with local font files (source: file) in a Reveal.js format, the @font-face declarations generated by the brand system use paths relative to the project root (e.g., fonts/FiraCode-Regular.ttf).
These paths are correct for the HTML format (where the CSS resolves from the document root), but incorrect for Reveal.js.

In Reveal.js, the brand-generated CSS is placed inside the theme at {output}_files/libs/revealjs/dist/theme/, so Pandoc resolves the font URLs relative to that directory, producing invalid paths like:

{output}_files/libs/revealjs/dist/theme/fonts/FiraCode-Regular.ttf

This causes [WARNING] Could not fetch resource for every font file and results in fonts not being embedded when embed-resources: true is set.

Reproducible example

https://github.com/mcanouil/quarto-issues-experiments/tree/main/quarto-cli-14284

_brand.yml:

color:
  primary: "#00C072"

typography:
  fonts:
    - family: Fira Code
      source: file
      files:
        - path: fonts/FiraCode-Regular.ttf
          weight: 400
          style: normal
  base:
    family: Fira Code

example.qmd:

---
title: Brand fonts in Reveal.js
format:
  revealjs:
    embed-resources: true
---

quarto render example.qmd

Expected behaviour

Font files should be resolved relative to the project root (same as in the HTML format) and embedded correctly when embed-resources: true.

Actual behaviour

[WARNING] Could not fetch resource example_files/libs/revealjs/dist/theme/fonts/FiraCode-Regular.ttf
Output created: example.html

The @font-face declarations exist in the output CSS but point to non-existent paths.
Fonts are not embedded and fall back to browser defaults.

Comparison with HTML format

The same _brand.yml works correctly for the html format.
The HTML format resolves @font-face URLs from the document root, where fonts/... is a valid path.

Workaround

Inject @font-face declarations via include-in-header with a <style> block.
Resources referenced from <style> blocks in the HTML <head> are resolved relative to the document root, so the paths work correctly.

format:
  revealjs:
    embed-resources: true
    include-in-header:
      - fonts.html

Where fonts.html contains:

<style>
  @font-face {
    font-family: "Fira Code";
    src: url("fonts/FiraCode-Regular.ttf");
    font-weight: 400;
    font-style: normal;
  }
</style>

The brand-generated @font-face warnings still appear, but the include-in-header fonts are resolved and embedded correctly.

Environment

Quarto 1.9.36
[✓] Checking environment information...
      Quarto cache location: /home/mcanouil/.cache/quarto
[✓] Checking versions of quarto binary dependencies...
      Pandoc version 3.8.3: OK
      Dart Sass version 1.87.0: OK
      Deno version 2.4.5: OK
      Typst version 0.14.2: OK
[✓] Checking versions of quarto dependencies......OK
[✓] Checking Quarto installation......OK
      Version: 1.9.36
      Path: /opt/quarto/bin
[✓] Checking tools....................OK
      TinyTeX: (not installed)
      Chromium: (not installed)
[✓] Checking LaTeX....................OK
      Tex:  (not detected)
[✓] Checking basic markdown render....OK
[✓] Checking R installation...........OK
      Version: 4.5.2
      Path: /opt/R/4.5.2/lib/R
      knitr: 1.51
      rmarkdown: 2.30
[✓] Checking Knitr engine render......OK
[✓] Checking Python 3 installation....OK
      Version: 3.12.3
      Path: /usr/bin/python3
      Jupyter: (None)

OS: Linux (WSL2)

Dominant language: JavaScript
Stars: 6k
Forks: 458
Avg merge: 1d 9h
Merged PRs (30d): 41

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