HTML does not show tikz figures

[lorenzoFabbri]

I am compiling a tex file to PDF and HTML with GitHub Actions. The complete repository can be found here. The PDF looks good, but the HTML does not. One problem is that the tikz figures are not displayed at all, there is only the caption. A second, perhaps minor, issue is that the equations are not really looking that good: they are not malformatted, but they do not look as good as in the PDF. I am new to using Actions and actions-gh-pages.

I copy the yml file here:

name: Build and Deploy LaTeX document
permissions: write-all

on:
  push:
    branches: [ "main" ]

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4.1.7
      - uses: xu-cheng/latex-action@3.2.0
        with:
          root_file: main.tex
      - uses: docker://ghcr.io/michal-h21/make4ht-action:latest
        env:
          command: "make4ht -u -f html5+dvisvgm_hashes -d out main.tex"
      - run: |
          cd out
          sudo mv main.html index.html
      - uses: actions/upload-artifact@v4.3.3
        with:
          name: main-pdf
          path: main.pdf
      - uses: softprops/action-gh-release@v2.0.6
        with:
          tag_name: Current
          files: main.pdf
      - uses: peaceiris/actions-gh-pages@v4.0.0
        with:
          github_token: ${{ secrets.GH_PAT }}
          publish_dir: ./out