How to find MacOS user fonts with mainfont when rendering to html?

[ViktorHaag]

Description

Quarto cannot find fonts installed in my ~/Library/Fonts directory for use with HTML rendering. I have tried the mainfont option in my YML in this simple test file:

---
title: Are my fonts included?
format:
    html:
        mainfont: "Gentium"
---

# Heading

The quick brown fox jumps over the lazy dog.

I have also tried using a custom scss file (instead of `main font: "Gentium" above, replace for "custom: custom.scss"), with this custom styles file:

/*-- scss:defaults --*/
$font-family-sans-serif:     "Gentium", -apple-system;

/*-- scss:rules --*/
@font-face{
    font-family: 'Gentium';
    src: url('/Users/vhaag/Library/Fonts/Gentium.ttc') format('truetype');
}

I believe that Quarto is finding this custom file because the output in rendering changes from using a basement of 'Times' to 'AppleSystemUIFont'.

However, I can't prod Quarto into finding this font and loading it. I have also tried copying the font file into the same directory as the test file so that the src url becomes ./Gentium.ttc. No joy.

How exactly is one supposed to find user-installed fonts on a MacOS install (the ones in the user's own Library directory)? Quarto also seems generally unable to find fonts installed into /Library/Fonts: I have tried installing the Gentium TTC file into that directory for a system-wide install: the Font Book app finds the font fine in either location (system-wide Library/Fonts, or user Library/Fonts) and validates the font file fine in both locations.

System and tools

MacOs Ventura (13.7.7)
Quarto 1.7.32 (tried also with latest Quarto 1.8.x dev build)
Quarto check output:

Quarto 1.7.32
[✓] Checking environment information...
      Quarto cache location: /Users/vhaag/Library/Caches/quarto
[✓] Checking versions of quarto binary dependencies...
      Pandoc version 3.6.3: OK
      Dart Sass version 1.85.1: OK
      Deno version 1.46.3: OK
      Typst version 0.13.0: OK
[✓] Checking versions of quarto dependencies......OK
[✓] Checking Quarto installation......OK
      Version: 1.7.32
      Path: /Applications/quarto/bin

[✓] Checking tools....................OK
      TinyTeX: (not installed)
      Chromium: (not installed)

[✓] Checking LaTeX....................OK
      Using: Installation From Path
      Path: /Library/TeX/texbin
      Version: 2022

[✓] Checking Chrome Headless....................OK
      Using: Chrome found on system
      Path: /Applications/Google Chrome.app/Contents/MacOS/Google Chrome
      Source: MacOS known location

[✓] Checking basic markdown render....OK

[✓] Checking Python 3 installation....OK
      Version: 3.13.5
      Path: /Users/vhaag/.pyenv/versions/3.13.5/bin/python3
      Jupyter: 5.8.1
      Kernels: python3

[✓] Checking Jupyter engine render....OK

[✓] Checking R installation...........(None)

      Unable to locate an installed version of R.
      Install R from https://cloud.r-project.org/

[cscheid]

How exactly is one supposed to find user-installed fonts on a MacOS install (the ones in the user's own Library directory)?

This is a question specific to HTML formats. It's not Quarto doing the font resolving in an .html file, it's your web browser seeing the name 'Gentium' and attempting to map it to some font (maybe in your filesystem, maybe elsewhere). You're probably better served by searching for solutions to that.

[ViktorHaag]

Thanks for that; it swiftly becomes apparent that Safari can only find fonts in the System's path (or as a webfont resource), while other browsers can search more widely for fonts on MacOS.