epub fig-align only works for unnumbered figures

I have:

• searched the issue tracker for similar issues
• installed the latest version of Quarto CLI
• formatted my issue following the Bug Reports guide

Bug description

The epub format has an option to specify figure alignment, e.g., fig-align: center. However, this option seems to only be respected for unnumbered figures, while numbered figures are left-aligned.

Steps to reproduce

Minimal working example:

---
title: "Fig Align Example"
format:
  epub:
    fig-align: center
---

Some text and an unnumbered figure....

![Elephant](elephant.png){width=40%}

Some more text and a numbered figure @fig-elephant

![Elephant](elephant.png){width=40% #fig-elephant}

Actual behavior

Epub output:

Expected behavior

Both images should be center-aligned.

Your environment

• Sublime Text
• MacOS 15.6.1

Quarto check output

Quarto 1.8.21
[✓] Checking environment information...
Quarto cache location: /Users/franzi/Library/Caches/quarto
[✓] Checking versions of quarto binary dependencies...
Pandoc version 3.6.3: OK
Dart Sass version 1.87.0: OK
Deno version 2.3.1: OK
Typst version 0.13.0: OK
[✓] Checking versions of quarto dependencies......OK
[✓] Checking Quarto installation......OK
Version: 1.8.21
Path: /Users/franzi/Applications/quarto/bin

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

[✓] Checking LaTeX....................OK
Using: Installation From Path
Path: /Library/TeX/texbin
Version: 2023

[✓] 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: 3.12.9
Path: /Users/franzi/.venv/bin/python3
Jupyter: 5.7.2
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/

Start by running the minimal working example with Quarto CLI and inspecting the generated EPUB, comparing the unnumbered and numbered figures. Trace the EPUB figure rendering path to find why alignment differs, then verify that both figures are centered in the generated output.